JANUS ASPEN SERIES
497, 2000-05-04
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<PAGE>


                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Growth Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                Growth Portfolio (the "Portfolio") is a mutual fund in Janus
                Aspen Series and is described in this prospectus. The Portfolio
                currently offers three classes of shares. The Service Shares,
                (the "Shares"), are offered by this prospectus in connection
                with investment in and payments under variable annuity contracts
                and variable life insurance contracts (collectively, "variable
                insurance contracts"), as well as certain qualified retirement
                plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. See the accompanying
                contract prospectus for information regarding contract fees and
                expenses and any restrictions on purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolio.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Growth Portfolio.........................................    2
                   Fees and expenses........................................    4
                INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Growth Portfolio.........................................    5
                   General portfolio policies...............................    7
                   Risks for Growth Portfolio...............................    9
                MANAGEMENT OF THE PORTFOLIO
                   Investment adviser.......................................   11
                   Management expenses and expense limits...................   11
                   Investment personnel.....................................   12
                OTHER INFORMATION...........................................   13
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   15
                   Taxes....................................................   15
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   16
                   Purchases................................................   16
                   Redemptions..............................................   16
                   Frequent trading.........................................   17
                   Shareholder communications...............................   17
                FINANCIAL HIGHLIGHTS........................................   18
                GLOSSARY
                   Glossary of investment terms.............................   19

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

GROWTH PORTFOLIO

          Growth Portfolio is designed for long-term investors who seek growth
          of capital and who can tolerate the greater risks associated with
          common stock investments.

1. WHAT IS THE INVESTMENT OBJECTIVE OF GROWTH PORTFOLIO?

- --------------------------------------------------------------------------------

          - GROWTH PORTFOLIO seeks long-term growth of capital in a manner
            consistent with the preservation of capital.

          The Portfolio's Trustees may change this objective without a
          shareholder vote and the Portfolio will notify you of any changes that
          are material. If there is a material change to the Portfolio's
          objective or policies, you should consider whether the Portfolio
          remains an appropriate investment for you. There is no guarantee that
          the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF GROWTH PORTFOLIO?

          The portfolio manager applies a "bottom up" approach in choosing
          investments. In other words, he looks for companies with earnings
          growth potential one at a time. If the portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of the Portfolio's assets may be in cash or similar investments.

          Growth Portfolio invests primarily in common stocks selected for their
          growth potential. Although the Portfolio can invest in companies of
          any size, it generally invests in larger, more established companies.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN GROWTH PORTFOLIO?

          The biggest risk of investing in this Portfolio is that its returns
          may vary, and you could lose money. If you are considering investing
          in Growth Portfolio, remember that it is designed for long-term
          investors who can accept the risks of investing in a portfolio with
          significant common stock holdings. Common stocks tend to be more
          volatile than other investment choices.

          The value of the Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of the
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of the Portfolio's holdings decreases, the
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in the Portfolio you would get back less money.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in Growth Portfolio by showing how Growth Portfolio's
          performance has varied over time. The Portfolio's Service Shares
          commenced operations on December 31, 1999. The returns shown for the
          Service Shares of the Portfolio reflect the historical performance of
          a different class of shares (the Institutional Shares) prior to
          December 31, 1999, restated based on the Service Shares' estimated
          fees and expenses (ignoring any fee and expense limitations). The bar
          chart depicts the change in performance from year-to-year during the
          period indicated but does not include charges and expenses
          attributable to any insurance product which would lower the
          performance illustrated. The Portfolio does not impose any sales or
          other charges that would affect total return computations. Total
          return figures include the effect of the Portfolio's expenses. The
          table compares the average annual returns for the Service Shares of
          the Portfolio for the periods indicated to a broad-based securities
          market index.

 2 Janus Aspen Series
<PAGE>

           GROWTH PORTFOLIO


Annual Returns for Periods Ended 12/31

                    2.71%     29.96%    18.14%    22.49%    35.59%    43.01%
                     1994      1995      1996      1997      1998      1999

Best Quarter  4th-1998  27.71%   Worst Quarter 3rd-1998 (10.95%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Growth Portfolio                                          43.01%    29.53%         23.86%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                                                                      --------------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

          Growth Portfolio's past performance does not necessarily indicate how
          it will perform in the future.

                                                          Risk return summary  3
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolio. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of the Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolio in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                              Distribution                             Total Annual
                                        Management               (12b-1)              Other           Fund Operating
                                            Fee                  Fees(1)            Expenses            Expenses(2)
    <S>                                 <C>                   <C>                   <C>               <C>
    Growth Portfolio                       0.65%                  0.25%               0.02%                0.92%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of the Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolio with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in the Portfolio for the time
   periods indicated then redeem all of your shares at the end of those
   periods. The example also assumes that your investment has a 5% return
   each year, and that the Portfolio's operating expenses remain the same.
   Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Growth Portfolio                                                $94       $293
</TABLE>

 4 Janus Aspen Series
<PAGE>
                                      Investment objective, principal investment
                                                 strategies and risks

          Growth Portfolio has a similar investment objective and similar
          principal investment strategies to Janus Fund. Although it is
          anticipated that the Portfolio and Janus Fund will hold similar
          securities, differences in asset size, cash flow needs and other
          factors may result in differences in investment performance. The
          expenses of the Portfolio and Janus Fund are expected to differ. The
          variable contract owner will also bear various insurance related costs
          at the insurance company level. You should review the accompanying
          separate account prospectus for a summary of fees and expenses.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          This section takes a closer look at the investment objective of Growth
          Portfolio, its principal investment strategies and certain risks of
          investing in Growth Portfolio. Strategies and policies that are noted
          as "fundamental" cannot be changed without a shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 9-10 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

          Growth Portfolio seeks long-term growth of capital in a manner
          consistent with the preservation of capital. It pursues its objective
          by investing primarily in common stocks selected for their growth
          potential. Although the Portfolio can invest in companies of any size,
          it generally invests in larger, more established companies.

The following questions and answers are designed to help you better understand
Growth Portfolio's principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          The Portfolio may invest substantially all of its assets in common
          stocks if the portfolio manager believes that common stocks will
          appreciate in value. The portfolio manager generally takes a "bottom
          up" approach to selecting companies. In other words, he seeks to
          identify individual companies with earnings growth potential that may
          not be recognized by the market at large. He makes this assessment by
          looking at companies one at a time, regardless of size, country of
          organization, place of principal business activity, or other similar
          selection criteria. Realization of income is not a significant
          consideration when choosing investments for the Portfolio. Income
          realized on the Portfolio's investments may be incidental to its
          objective.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio manager seeks companies that meet his
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolio may invest and the
          Portfolio may at times have significant foreign exposure.

              Investment objective, principal investment strategies and risks  5
<PAGE>

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. Although Growth Portfolio does not emphasize
          companies of any particular size, a Portfolio with a larger asset base
          is more likely to invest in larger, more established issuers.

 6 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          In investing its portfolio assets, the Portfolio will follow the
          general policies listed below. The percentage limitations included in
          these policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if the Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When the portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he is otherwise unable
          to locate attractive investment opportunities, the Portfolio's cash or
          similar investments may increase. In other words, the Portfolio does
          not always stay fully invested in stocks and bonds. Cash or similar
          investments generally are a residual - they represent the assets that
          remain after the portfolio manager has committed available assets to
          desirable investment opportunities. However, the portfolio manager may
          also temporarily increase the Portfolio's cash position to protect its
          assets or maintain liquidity.

          When the Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          Growth Portfolio invests primarily in domestic and foreign equity
          securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Portfolio may also invest to a lesser degree in other types of
          securities. These securities (which are described in the Glossary) may
          include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of the Portfolio's assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          The Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolio's Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolio may invest without limit in foreign equity and debt
          securities. The Portfolio may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

              Investment objective, principal investment strategies and risks  7
<PAGE>

          SPECIAL SITUATIONS
          The Portfolio may invest in special situations. A special situation
          arises when, in the opinion of the Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. The Portfolio's performance
          could suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolio generally intends to purchase securities for long-term
          investment although, to a limited extent, the Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. The Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in the Portfolio's holdings whenever the
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in the Portfolio's
          performance.

 8 Janus Aspen Series
<PAGE>

RISKS FOR GROWTH PORTFOLIO

          Because the Portfolio may invest substantially all of its assets in
          common stocks, the main risk is the risk that the value of the stocks
          it holds might decrease in response to the activities of an individual
          company or in response to general market and/or economic conditions.
          If this occurs, the Portfolio's share price may also decrease. The
          Portfolio's performance may also be affected by risks specific to
          certain types of investments, such as foreign securities, derivative
          investments, non-investment grade debt securities, initial public
          offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in Growth Portfolio.

1. THE PORTFOLIO MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW COULD THE PORTFOLIO'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
   PERFORMANCE?

          The Portfolio may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolio's performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as the Portfolio holds a foreign security,
            its value will be affected by the value of the local currency
            relative to the U.S. dollar. When the Portfolio sells a foreign
            denominated security, its value may be worth less in U.S. dollars
            even if the security increases in value in its home country. U.S.
            dollar denominated securities of foreign issuers may also be
            affected by currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may take over the assets or operations of a company or
            that the government may impose taxes or limits on the removal of the
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

              Investment objective, principal investment strategies and risks  9
<PAGE>

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

3. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

4. HOW DOES THE PORTFOLIO TRY TO REDUCE RISK?

          The Portfolio may use futures, options, swaps and other derivative
          instruments to "hedge" or protect its portfolio from adverse movements
          in securities prices and interest rates. The Portfolio may also use a
          variety of currency hedging techniques, including forward currency
          contracts, to manage exchange rate risk. The portfolio manager
          believes the use of these instruments will benefit the Portfolio.
          However, the Portfolio's performance could be worse than if the
          Portfolio had not used such instruments if the portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 10 Janus Aspen Series
<PAGE>
                                                     Management of the portfolio

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to the Portfolio and is responsible for the
          day-to-day management of the investment portfolio and other business
          affairs of the Portfolio.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning the Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolio, and may be reimbursed by the Portfolio for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolio and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolio's Shares
          may perform certain administrative services relating to the Portfolio
          and Janus Capital or the Portfolio may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          The Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with the Portfolio
          spells out the management fee and other expenses that the Portfolio
          must pay. In addition, the Shares of the Portfolio incur expenses not
          assumed by Janus Capital, including the distribution fee, transfer
          agent and custodian fees and expenses, legal and auditing fees,
          printing and mailing costs of sending reports and other information to
          existing shareholders, and independent Trustees' fees and expenses.
          The Portfolio expects to pay Janus Capital a management fee equal to
          0.65% of average daily net assets during the fiscal year ended
          December 31, 2000. For the fiscal year ended December 31, 1999, the
          Portfolio paid Janus Capital a management fee equal to 0.67% of the
          Portfolio's average net assets. This rate is based on a higher fee
          rate that was previously in effect.

                                                 Management of the portfolio  11
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGER

BLAINE P. ROLLINS
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Growth
            Portfolio as of January 2000. He previously managed Balanced
            Portfolio from May 1996 to December 1999 and Equity Income
            Portfolio from its inception to December 1999. Mr. Rollins joined
            Janus Capital in 1990 and has managed Janus Fund since January
            2000, Janus Balanced Fund from January 1996 until December 1999
            and Janus Equity Income Fund from inception until December 1999.
            He was an assistant portfolio manager of Janus Fund from January
            1994 until December 1999. He gained experience as a fixed-income
            trader and equity research analyst prior to managing Balanced
            Portfolio. He holds a Bachelor of Science in Finance from the
            University of Colorado and he has earned the right to use the
            Chartered Financial Analyst designation.

ASSISTANT PORTFOLIO MANAGERS

DAVID C. DECKER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. He is also
            an assistant portfolio manager of Janus Fund. He is Executive
            Vice President and portfolio manager of Strategic Value
            Portfolio, Janus Strategic Value Fund and Janus Special
            Situations Fund, each of which he has managed since its
            inception. He obtained a Masters of Business Administration in
            Finance from the Fuqua School of Business at Duke University and
            a Bachelor of Arts in Economics and Political Science from Tufts
            University. Mr. Decker has earned the right to use the Chartered
            Financial Analyst designation.

KAREN L. REIDY
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Balanced
            Portfolio and Equity Income Portfolio as of January 2000, and an
            assistant portfolio manager of Growth Portfolio since 1998. She
            also manages Janus Balanced Fund and Janus Equity Income Fund as
            of January 2000. She is also assistant portfolio manager of Janus
            Fund. Prior to joining Janus Capital in 1995, she worked for
            Price Waterhouse as a manager in both the Mergers and
            Acquisitions and Audit business units. In this capacity, Ms.
            Reidy performed due diligence work for corporate clients and
            oversaw audit engagements. She received an undergraduate degree
            in Accounting from the University of Colorado in 1989 and passed
            the CPA exam in 1992. She has earned the right to use the
            Chartered Financial Analyst designation.

JOHN H. SCHREIBER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. Mr.
            Schreiber joined Janus Capital in 1997 as an equity research
            analyst. Prior to coming to Janus he was an equity analyst with
            Fidelity Investments. Mr. Schreiber holds a Bachelor of Science
            degree in mechanical engineering from the University of
            Washington and an MBA from Harvard University.

 12 Janus Aspen Series
<PAGE>
                                                               Other information

          CLASSES OF SHARES

          The Portfolio currently offers three classes of shares, one of which,
          the Service Shares, are offered pursuant to this prospectus. The
          Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of the
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of the Portfolio are
          offered only to qualified plans using plan service providers that are
          compensated for providing distribution and/or record keeping and other
          administrative services provided to plan participants. Because the
          expenses of each class may differ, the performance of each class is
          expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, the Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of the Portfolio. Under the
          terms of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolio does not currently anticipate any disadvantages to
          owners of variable insurance contracts because the Portfolio offers
          its shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in the Portfolio or substitute Shares of
          another Portfolio. If this occurs, the Portfolio may be forced to sell
          its securities at disadvantageous prices. In addition, the Trustees
          may refuse to sell Shares of the Portfolio to any separate account or
          qualified plan or may suspend or terminate the offering of the
          Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of the Portfolio's shareholders.
          It is possible that a qualified plan investing in the Portfolio could
          lose its qualified plan status under the Internal Revenue Code, which
          could have adverse tax consequences on insurance company separate
          accounts investing in the Shares. Janus Capital intends to monitor
          such qualified plans and the Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if a plan loses (or in the
          opinion of Janus Capital is at risk of losing) its qualified plan
          status.

                                                           Other information  13
<PAGE>

          DISTRIBUTION OF THE PORTFOLIO

          The Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

 14 Janus Aspen Series
<PAGE>
                                                         Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolio, the Internal Revenue Code requires
          the Portfolio to distribute net income and any net gains realized on
          its investments annually. The Portfolio's income from dividends and
          interest and any net realized short-term gains are paid to
          shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of the Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of the Portfolio will automatically be
          reinvested into additional Shares of the Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of the Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of the Portfolio's Shares. The Share price of the Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Growth Portfolio declared a dividend in the amount of $0.25 per share.
          If the price of Growth Portfolio's Shares was $10.00 on December 30,
          the share price on December 31 would be $9.75, barring market
          fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolio may be purchased only through variable
          insurance contracts and qualified plans, it is anticipated that any
          income dividends or capital gains distributions made by the Shares of
          the Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIO

          Dividends, interest and some gains received by the Portfolio on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolio may from year to year make the election permitted
          under Section 853 of the Internal Revenue Code to pass through such
          taxes to shareholders as a foreign tax credit. If such election is not
          made, any foreign taxes paid or accrued will represent an expense to
          the Portfolio which will reduce its investment income.

          The Portfolio does not expect to pay any federal income or excise
          taxes because it intends to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of the Portfolio
          are sold in connection with variable insurance contracts, the
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  15
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIO DIRECTLY.
          SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE INSURANCE
          CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING INSURANCE
          COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. REFER TO THE
          PROSPECTUS FOR THE PARTICIPATING INSURANCE COMPANY'S SEPARATE ACCOUNT
          OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON PURCHASING OR SELLING OF
          VARIABLE INSURANCE CONTRACTS AND ON HOW TO SELECT THE PORTFOLIO AS AN
          INVESTMENT OPTION FOR A CONTRACT OR A QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by the Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolio are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent the Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolio does not price its shares, the NAV of the Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of the Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolio's behalf.

          The Portfolio does not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. The Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of the Portfolio. Although there is no present
          intention to do so, the Portfolio may discontinue sales of its shares
          if management and the Trustees believe that continued sales may
          adversely affect the Portfolio's ability to achieve its investment
          objective. If sales of the Portfolio's Shares are discontinued, it is
          expected that existing participants invested in the Portfolio would be
          permitted to continue to authorize investment in the Portfolio and to
          reinvest any dividends or capital gains distributions, absent highly
          unusual circumstances. The Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of the Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption

 16 Janus Aspen Series
<PAGE>

          proceeds will normally be wired the business day following receipt of
          the redemption order, but in no event later than seven days after
          receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage the Portfolio's investments. The
          Portfolio does not permit frequent trading or market timing. When
          market timing occurs, the Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm the Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash the Portfolio will have to invest. When
          in Janus Capital's opinion such activity would have a disruptive
          effect on portfolio management, the Portfolio reserves the right to
          refuse purchase orders and exchanges into the Portfolio by any person,
          group or commonly controlled account. The Portfolio may notify a
          market timer of rejection of a purchase or exchange order after the
          day the order is placed. If the Portfolio allows a market timer to
          trade Portfolio shares, it may require the market timer to enter into
          a written agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolio that they have
          authorized for investment. Each report will show the investments owned
          by the Portfolio and the market values thereof, as well as other
          information about the Portfolio and its operations. The Trust's fiscal
          year ends December 31.

                                                         Shareholder's guide  17
<PAGE>
Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

 18 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolio may
          invest. The Portfolio may invest in these instruments to the extent
          permitted by its investment objective and policies. The Portfolio is
          not limited by this discussion and may invest in any other types of
          instruments not precluded by the policies discussed elsewhere in this
          Prospectus. Please refer to the SAI for a more detailed discussion of
          certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolio may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, the portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  19
<PAGE>

          Portfolio must pay if these investments are profitable, the Portfolio
          may make various elections permitted by the tax laws. These elections
          could require that the Portfolio recognize taxable income, which in
          turn must be distributed, before the securities are sold and before
          cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by the
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, the Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by the
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by the Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 20 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolio
          does not earn interest on such securities until settlement and bear
          the risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolio may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. It may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolio may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolio may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          The Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  21
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolio may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 22 Janus Aspen Series
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolio.

The Statement of Additional Information provides detailed
information about the Portfolio and is incorporated into this
Prospectus by reference. You may review the Portfolio's Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>
                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Aggressive Growth Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                Aggressive Growth Portfolio (the "Portfolio") is a mutual fund
                in Janus Aspen Series and is described in this prospectus. The
                Portfolio currently offers three classes of shares. The Service
                Shares, (the "Shares"), are offered by this prospectus in
                connection with investment in and payments under variable
                annuity contracts and variable life insurance contracts
                (collectively, "variable insurance contracts"), as well as
                certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. See the accompanying
                contract prospectus for information regarding contract fees and
                expenses and any restrictions on purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolio.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Aggressive Growth Portfolio..............................    2
                   Fees and expenses........................................    4
                INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Aggressive Growth Portfolio..............................    5
                   General portfolio policies...............................    7
                   Risks for Aggressive Growth Portfolio....................    9
                MANAGEMENT OF THE PORTFOLIO
                   Investment adviser.......................................   11
                   Management expenses and expense limits...................   11
                   Investment personnel.....................................   12
                OTHER INFORMATION...........................................   13
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   15
                   Taxes....................................................   15
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   16
                   Purchases................................................   16
                   Redemptions..............................................   16
                   Frequent trading.........................................   17
                   Shareholder communications...............................   17
                FINANCIAL HIGHLIGHTS........................................   18
                GLOSSARY
                   Glossary of investment terms.............................   19

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

AGGRESSIVE GROWTH PORTFOLIO

          Aggressive Growth Portfolio is designed for long-term investors who
          seek growth of capital and who can tolerate the greater risks
          associated with common stock investments.

1. WHAT IS THE INVESTMENT OBJECTIVE OF AGGRESSIVE GROWTH PORTFOLIO?

- --------------------------------------------------------------------------------

          - AGGRESSIVE GROWTH PORTFOLIO seeks long-term growth of capital.

          The Portfolio's Trustees may change this objective without a
          shareholder vote and the Portfolio will notify you of any changes
          that are material. If there is a material change to the Portfolio's
          objective or policies, you should consider whether the Portfolio
          remains an appropriate investment for you. There is no guarantee
          that the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF AGGRESSIVE GROWTH PORTFOLIO?

          The portfolio manager applies a "bottom up" approach in choosing
          investments. In other words, he looks for companies with earnings
          growth potential one at a time. If the portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of the Portfolio's assets may be in cash or similar investments.

          Aggressive Growth Portfolio invests primarily in common stocks
          selected for their growth potential, and normally invests at least 50%
          of its equity assets in medium-sized companies.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN AGGRESSIVE GROWTH PORTFOLIO?

          The biggest risk of investing in this Portfolio is that its returns
          may vary, and you could lose money. If you are considering investing
          in Aggressive Growth Portfolio, remember that it is designed for
          long-term investors who can accept the risks of investing in a
          portfolio with significant common stock holdings. Common stocks tend
          to be more volatile than other investment choices.

          The value of the Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of the
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of the Portfolio's holdings decreases, the
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in the Portfolio you would get back less money.

          The Portfolio is nondiversified. In other words, it may hold larger
          positions in a smaller number of securities than a diversified fund.
          As a result, a single security's increase or decrease in value may
          have a greater impact on the Portfolio's NAV and total return.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

 2 Janus Aspen Series
<PAGE>

          The following information provides some indication of the risks of
          investing in Aggressive Growth Portfolio by showing how Aggressive
          Growth Portfolio's performance has varied over time. The Portfolio's
          Service Shares commenced operations on December 31, 1999. The returns
          shown for the Service Shares of the Portfolio reflect the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses (ignoring any fee and expense
          limitations). The bar chart depicts the change in performance from
          year-to-year during the period indicated but does not include charges
          and expenses attributable to any insurance product which would lower
          the performance illustrated. The Portfolio does not impose any sales
          or other charges that would affect total return computations. Total
          return figures include the effect of the Portfolio's expenses. The
          table compares the average annual returns for the Service Shares of
          the Portfolio for the periods indicated to a broad-based securities
          market index.

           Annual Returns for Periods Ended 12/31

                            16.33%   27.38%    7.72%   12.53%   34.19%   123.16%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1999  58.17%  Worst Quarter  3rd-1998 (15.00%)

                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                         1 year     5 years       (9/13/93)
                <S>                                                      <C>        <C>        <C>
                Aggressive Growth Portfolio                              123.16%    35.83%         33.98%
                S&P MidCap 400 Index*                                     14.72%    23.05%         18.08%
                                                                     ---------------------------------------------
</TABLE>

           * The S&P MidCap 400 Index is an unmanaged group of 400 domestic
             stocks chosen for their market size, liquidity and industry group
             representation.

          Aggressive Growth Portfolio's past performance does not necessarily
          indicate how it will perform in the future.

                                                          Risk return summary  3
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolio. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of the Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolio in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                           Distribution                   Total Annual
                                         Management           (12b-1)        Other       Fund Operating
                                             Fee              Fees(1)       Expenses       Expenses(2)
    <S>                                  <C>               <C>              <C>          <C>
    Aggressive Growth Portfolio             0.65%              0.25%          0.02%          0.92%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of the Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolio with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in the Portfolio for the time
   periods indicated then redeem all of your shares at the end of those
   periods. The example also assumes that your investment has a 5% return
   each year, and that the Portfolio's operating expenses remain the same.
   Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Aggressive Growth Portfolio                                     $94       $293
</TABLE>

 4 Janus Aspen Series
<PAGE>
                                      Investment objective, principal investment
                                                 strategies and risks

          Aggressive Growth Portfolio has a similar investment objective and
          similar principal investment strategies to Janus Enterprise Fund.
          Although it is anticipated that the Portfolio and Janus Enterprise
          Fund will hold similar securities, differences in asset size, cash
          flow needs and other factors may result in differences in investment
          performance. The expenses of the Portfolio and Janus Enterprise Fund
          are expected to differ. The variable contract owner will also bear
          various insurance related costs at the insurance company level. You
          should review the accompanying separate account prospectus for a
          summary of fees and expenses.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          This section takes a closer look at the investment objective of
          Aggressive Growth Portfolio, its principal investment strategies and
          certain risks of investing in Aggressive Growth Portfolio. Strategies
          and policies that are noted as "fundamental" cannot be changed without
          a shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 9-10 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

          Aggressive Growth Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential, and normally invests at least 50% of its
          equity assets in medium-sized companies. Medium-sized companies are
          those whose market capitalization falls within the range of companies
          in the S&P MidCap 400 Index. Market capitalization is a commonly used
          measure of the size and value of a company. The market capitalizations
          within the Index will vary, but as of December 31, 1999, they ranged
          from approximately $170 million to $37 billion.

The following questions and answers are designed to help you better understand
Aggressive Growth Portfolio's principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          The Portfolio may invest substantially all of its assets in common
          stocks if the portfolio manager believes that common stocks will
          appreciate in value. The portfolio manager generally takes a "bottom
          up" approach to selecting companies. In other words, he seeks to
          identify individual companies with earnings growth potential that may
          not be recognized by the market at large. He makes this assessment by
          looking at companies one at a time, regardless of size, country of
          organization, place of principal business activity, or other similar
          selection criteria. Realization of income is not a significant
          consideration when choosing investments for the Portfolio. Income
          realized on the Portfolio's investments may be incidental to its
          objective.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio manager seeks companies that meet his
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolio may invest and the
          Portfolio may at times have significant foreign exposure.

              Investment objective, principal investment strategies and risks  5
<PAGE>

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. As noted previously, market capitalization is
          an important investment criteria for Aggressive Growth Portfolio.

 6 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          In investing its portfolio assets, the Portfolio will follow the
          general policies listed below. The percentage limitations included in
          these policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if the Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When the portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he is otherwise unable
          to locate attractive investment opportunities, the Portfolio's cash or
          similar investments may increase. In other words, the Portfolio does
          not always stay fully invested in stocks and bonds. Cash or similar
          investments generally are a residual - they represent the assets that
          remain after the portfolio manager has committed available assets to
          desirable investment opportunities. However, the portfolio manager may
          also temporarily increase the Portfolio's cash position to protect its
          assets or maintain liquidity.

          When the Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          Aggressive Growth Portfolio invests primarily in domestic and foreign
          equity securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Portfolio may also invest to a lesser degree in other types of
          securities. These securities (which are described in the Glossary) may
          include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of the Portfolio's assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          The Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolio's Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolio may invest without limit in foreign equity and debt
          securities. The Portfolio may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

              Investment objective, principal investment strategies and risks  7
<PAGE>

          SPECIAL SITUATIONS
          The Portfolio may invest in special situations. A special situation
          arises when, in the opinion of the Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. The Portfolio's performance
          could suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolio generally intends to purchase securities for long-term
          investment although, to a limited extent, the Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. The Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in the Portfolio's holdings whenever the
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in the Portfolio's
          performance.

 8 Janus Aspen Series
<PAGE>

RISKS FOR AGGRESSIVE GROWTH PORTFOLIO

          Because the Portfolio may invest substantially all of its assets in
          common stocks, the main risk is the risk that the value of the stocks
          it holds might decrease in response to the activities of an individual
          company or in response to general market and/or economic conditions.
          If this occurs, the Portfolio's share price may also decrease. The
          Portfolio's performance may also be affected by risks specific to
          certain types of investments, such as foreign securities, derivative
          investments, non-investment grade bonds, initial public offerings
          (IPOs) or companies with relatively small market capitalizations. IPOs
          and other investment techniques may have a magnified performance
          impact on a portfolio with a small asset base. A portfolio may not
          experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in Aggressive Growth Portfolio.

1. THE PORTFOLIO MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF AGGRESSIVE GROWTH PORTFOLIO AFFECT ITS
   RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of the Portfolio.

3. HOW COULD THE PORTFOLIO'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
   PERFORMANCE?

          The Portfolio may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolio's performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as the Portfolio holds a foreign security,
            its value will be affected by the value of the local currency
            relative to the U.S. dollar. When the Portfolio sells a foreign
            denominated security, its value may be worth less in U.S. dollars
            even if the security increases in value in its home country. U.S.
            dollar denominated securities of foreign issuers may also be
            affected by currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may

              Investment objective, principal investment strategies and risks  9
<PAGE>

            take over the assets or operations of a company or that the
            government may impose taxes or limits on the removal of the
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

4. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

5. HOW DOES THE PORTFOLIO TRY TO REDUCE RISK?

          The Portfolio may use futures, options, swaps and other derivative
          instruments to "hedge" or protect its portfolio from adverse movements
          in securities prices and interest rates. The Portfolio may also use a
          variety of currency hedging techniques, including forward currency
          contracts, to manage exchange rate risk. The portfolio manager
          believes the use of these instruments will benefit the Portfolio.
          However, the Portfolio's performance could be worse than if the
          Portfolio had not used such instruments if the portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 10 Janus Aspen Series
<PAGE>
                                                     Management of the portfolio

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to the Portfolio and is responsible for the
          day-to-day management of the investment portfolio and other business
          affairs of the Portfolio.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning the Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolio, and may be reimbursed by the Portfolio for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolio and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolio's Shares
          may perform certain administrative services relating to the Portfolio
          and Janus Capital or the Portfolio may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          The Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with the Portfolio
          spells out the management fee and other expenses that the Portfolio
          must pay. In addition, the Shares of the Portfolio incur expenses not
          assumed by Janus Capital, including the distribution fee, transfer
          agent and custodian fees and expenses, legal and auditing fees,
          printing and mailing costs of sending reports and other information to
          existing shareholders, and independent Trustees' fees and expenses.
          The Portfolio expects to pay Janus Capital a management fee equal to
          0.65% of average daily net assets during the fiscal year ended
          December 31, 2000. For the fiscal year ended December 31, 1999, the
          Portfolio paid Janus Capital a management fee equal to 0.68% of the
          Portfolio's average net assets. This rate is based on a higher fee
          rate that was previously in effect.

                                                 Management of the portfolio  11
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGER

JAMES P. GOFF
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Aggressive
            Growth Portfolio, which he has managed since inception. Mr. Goff
            joined Janus Capital in 1988 and has managed Janus Enterprise
            Fund since its inception. Mr. Goff co-managed or managed Janus
            Venture Fund from December 1993 to February 1997. He holds a
            Bachelor of Arts in Economics from Yale University and he has
            earned the right to use the Chartered Financial Analyst
            designation.

ASSISTANT PORTFOLIO MANAGERS

MATTHEW A. ANKRUM
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            He is also assistant portfolio manager of Janus Enterprise Fund.
            Mr. Ankrum joined Janus Capital as an intern in June 1996, and
            became an equity research analyst in August 1997. Prior to
            joining Janus, Mr. Ankrum worked as a corporate finance analyst
            at William Blair and Company from 1993 through 1995. He was also
            a fixed-income research analyst at Conseco Capital Management.
            Mr. Ankrum has an undergraduate degree in Business Administration
            from the University of Wisconsin and a Master of Business
            Administration from the University of Chicago. Mr. Ankrum has
            earned the right to use the Chartered Financial Analyst
            designation.

RON SACHS
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            Mr. Sachs joined Janus Capital in 1996 as a research analyst.
            Prior to coming to Janus, he worked as a consultant for Bain &
            Company and as an attorney for Willkie, Farr & Gallagher. Mr.
            Sachs graduated from Princeton cum laude with an undergraduate
            degree in economics. He obtained his law degree from the
            University of Michigan. Mr. Sachs has earned the right to use the
            Chartered Financial Analyst designation.

 12 Janus Aspen Series
<PAGE>
                                                               Other information

          CLASSES OF SHARES

          The Portfolio currently offers three classes of shares, one of which,
          the Service Shares, are offered pursuant to this prospectus. The
          Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of the
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of the Portfolio are
          offered only to qualified plans using plan service providers that are
          compensated for providing distribution and/or record keeping and other
          administrative services provided to plan participants. Because the
          expenses of each class may differ, the performance of each class is
          expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, the Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of the Portfolio. Under the
          terms of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolio does not currently anticipate any disadvantages to
          owners of variable insurance contracts because the Portfolio offers
          its shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in the Portfolio or substitute Shares of
          another Portfolio. If this occurs, the Portfolio may be forced to sell
          its securities at disadvantageous prices. In addition, the Trustees
          may refuse to sell Shares of the Portfolio to any separate account or
          qualified plan or may suspend or terminate the offering of the
          Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of the Portfolio's shareholders.
          It is possible that a qualified plan investing in the Portfolio could
          lose its qualified plan status under the Internal Revenue Code, which
          could have adverse tax consequences on insurance company separate
          accounts investing in the Shares. Janus Capital intends to monitor
          such qualified plans and the Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if a plan loses (or in the
          opinion of Janus Capital is at risk of losing) its qualified plan
          status.

                                                           Other information  13
<PAGE>

          DISTRIBUTION OF THE PORTFOLIO

          The Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

 14 Janus Aspen Series
<PAGE>
                                                         Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolio, the Internal Revenue Code requires
          the Portfolio to distribute net income and any net gains realized on
          its investments annually. The Portfolio's income from dividends and
          interest and any net realized short-term gains are paid to
          shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of the Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of the Portfolio will automatically be
          reinvested into additional Shares of the Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of the Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of the Portfolio's Shares. The Share price of the Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Aggressive Growth Portfolio declared a dividend in the amount of $0.25
          per share. If the price of Aggressive Growth Portfolio's Shares was
          $10.00 on December 30, the share price on December 31 would be $9.75,
          barring market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolio may be purchased only through variable
          insurance contracts and qualified plans, it is anticipated that any
          income dividends or capital gains distributions made by the Shares of
          the Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIO

          Dividends, interest and some gains received by the Portfolio on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolio may from year to year make the election permitted
          under Section 853 of the Internal Revenue Code to pass through such
          taxes to shareholders as a foreign tax credit. If such election is not
          made, any foreign taxes paid or accrued will represent an expense to
          the Portfolio which will reduce its investment income.

          The Portfolio does not expect to pay any federal income or excise
          taxes because it intends to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of the Portfolio
          are sold in connection with variable insurance contracts, the
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  15
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIO DIRECTLY.
          SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE INSURANCE
          CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING INSURANCE
          COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. REFER TO THE
          PROSPECTUS FOR THE PARTICIPATING INSURANCE COMPANY'S SEPARATE ACCOUNT
          OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON PURCHASING OR SELLING OF
          VARIABLE INSURANCE CONTRACTS AND ON HOW TO SELECT THE PORTFOLIO AS AN
          INVESTMENT OPTION FOR A CONTRACT OR A QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by the Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolio are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent the Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolio does not price its shares, the NAV of the Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of the Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolio's behalf.

          The Portfolio does not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. The Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of the Portfolio. Although there is no present
          intention to do so, the Portfolio may discontinue sales of its shares
          if management and the Trustees believe that continued sales may
          adversely affect the Portfolio's ability to achieve its investment
          objective. If sales of the Portfolio's Shares are discontinued, it is
          expected that existing participants invested in the Portfolio would be
          permitted to continue to authorize investment in the Portfolio and to
          reinvest any dividends or capital gains distributions, absent highly
          unusual circumstances. The Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of the Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption

 16 Janus Aspen Series
<PAGE>

          proceeds will normally be wired the business day following receipt of
          the redemption order, but in no event later than seven days after
          receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage the Portfolio's investments. The
          Portfolio does not permit frequent trading or market timing. When
          market timing occurs, the Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm the Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash the Portfolio will have to invest. When
          in Janus Capital's opinion such activity would have a disruptive
          effect on portfolio management, the Portfolio reserves the right to
          refuse purchase orders and exchanges into the Portfolio by any person,
          group or commonly controlled account. The Portfolio may notify a
          market timer of rejection of a purchase or exchange order after the
          day the order is placed. If the Portfolio allows a market timer to
          trade Portfolio shares, it may require the market timer to enter into
          a written agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolio that they have
          authorized for investment. Each report will show the investments owned
          by the Portfolio and the market values thereof, as well as other
          information about the Portfolio and its operations. The Trust's fiscal
          year ends December 31.

                                                         Shareholder's guide  17
<PAGE>
Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

 18 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolio may
          invest. The Portfolio may invest in these instruments to the extent
          permitted by its investment objective and policies. The Portfolio is
          not limited by this discussion and may invest in any other types of
          instruments not precluded by the policies discussed elsewhere in this
          Prospectus. Please refer to the SAI for a more detailed discussion of
          certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolio may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, the portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  19
<PAGE>

          Portfolio must pay if these investments are profitable, the Portfolio
          may make various elections permitted by the tax laws. These elections
          could require that the Portfolio recognize taxable income, which in
          turn must be distributed, before the securities are sold and before
          cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by the
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, the Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by the
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by the Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 20 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolio
          does not earn interest on such securities until settlement and bear
          the risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolio may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. It may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolio may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolio may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          The Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  21
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolio may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 22 Janus Aspen Series
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolio.

The Statement of Additional Information provides detailed
information about the Portfolio and is incorporated into this
Prospectus by reference. You may review the Portfolio's Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>

                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Capital Appreciation Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                Capital Appreciation Portfolio (the "Portfolio") is a mutual
                fund in Janus Aspen Series and is described in this prospectus.
                The Portfolio currently offers three classes of shares. The
                Service Shares, (the "Shares"), are offered by this prospectus
                in connection with investment in and payments under variable
                annuity contracts and variable life insurance contracts
                (collectively, "variable insurance contracts"), as well as
                certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. See the accompanying
                contract prospectus for information regarding contract fees and
                expenses and any restrictions on purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolio.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Capital Appreciation Portfolio...........................    2
                   Fees and expenses........................................    4
                INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Capital Appreciation Portfolio...........................    5
                   General portfolio policies...............................    7
                   Risks for Capital Appreciation Portfolio.................    9
                MANAGEMENT OF THE PORTFOLIO
                   Investment adviser.......................................   11
                   Management expenses and expense limits...................   11
                   Investment personnel.....................................   12
                OTHER INFORMATION...........................................   13
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   15
                   Taxes....................................................   15
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   16
                   Purchases................................................   16
                   Redemptions..............................................   16
                   Frequent trading.........................................   17
                   Shareholder communications...............................   17
                FINANCIAL HIGHLIGHTS........................................   18
                GLOSSARY
                   Glossary of investment terms.............................   19

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

CAPITAL APPRECIATION PORTFOLIO

          Capital Appreciation Portfolio is designed for long-term investors who
          seek growth of capital and who can tolerate the greater risks
          associated with common stock investments.

1. WHAT IS THE INVESTMENT OBJECTIVE OF CAPITAL APPRECIATION PORTFOLIO?

- --------------------------------------------------------------------------------

          - CAPITAL APPRECIATION PORTFOLIO seeks long-term growth of capital.

          The Portfolio's Trustees may change this objective without a
          shareholder vote and the Portfolio will notify you of any changes that
          are material. If there is a material change to the Portfolio's
          objective or policies, you should consider whether the Portfolio
          remains an appropriate investment for you. There is no guarantee that
          the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF CAPITAL APPRECIATION PORTFOLIO?

          The portfolio manager applies a "bottom up" approach in choosing
          investments. In other words, he looks for companies with earnings
          growth potential one at a time. If the portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of the Portfolio's assets may be in cash or similar investments.

          Capital Appreciation Portfolio invests primarily in common stocks
          selected for their growth potential. The Portfolio may invest in
          companies of any size, from larger, well-established companies to
          smaller, emerging growth companies.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN CAPITAL APPRECIATION PORTFOLIO?

          The biggest risk of investing in this Portfolio is that its returns
          may vary, and you could lose money. If you are considering investing
          in Capital Appreciation Portfolio, remember that it is designed for
          long-term investors who can accept the risks of investing in a
          portfolio with significant common stock holdings. Common stocks tend
          to be more volatile than other investment choices.

          The value of the Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of the
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of the Portfolio's holdings decreases, the
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in the Portfolio you would get back less money.

          The Portfolio is nondiversified. In other words, it may hold larger
          positions in a smaller number of securities than a diversified fund.
          As a result, a single security's increase or decrease in value may
          have a greater impact on the Portfolio's NAV and total return.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in Capital Appreciation Portfolio by showing how Capital
          Appreciation Portfolio's performance has varied over time. The
          Portfolio's Service Shares commenced operations on December 31, 1999.
          The returns shown for the Service Shares of the Portfolio reflect the
          historical performance of a different class of shares (the
          Institutional Shares) prior to December 31, 1999, restated based on
          the Service Shares' estimated fees and expenses (ignoring any fee and
          expense limitations). The bar chart depicts the change in performance
          from year-to-year during the period indicated but does not include
          charges and expenses attributable to any insurance product which would
          lower the performance illustrated. The Portfolio does not impose any
          sales or other charges that

 2 Janus Aspen Series
<PAGE>

          would affect total return computations. Total return figures include
          the effect of the Portfolio's expenses. The table compares the average
          annual returns for the Service Shares of the Portfolio for the periods
          indicated to a broad-based securities market index.

           CAPITAL APPRECIATION PORTFOLIO

                                                                57.91%    64.60%
                                                                 1998      1999

           Best Quarter: 4th-1999 40.00% Worst Quarter: 3rd-1998 (9.99%)

                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                           Since Inception
                                                                                 1 year       (5/1/97)
                <S>                                                              <C>       <C>
                Capital Appreciation Portfolio                                   64.60%        56.39%
                S&P 500 Index*                                                   21.03%        27.40%
                                                                             --------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

          Capital Appreciation Portfolio's past performance does not necessarily
          indicate how it will perform in the future.

                                                          Risk return summary  3
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolio. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of the Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolio in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                          Distribution                         Total Annual Fund
                                         Management         (12b-1)               Other            Operating
                                            Fee             Fees(1)             Expenses          Expenses(2)
    <S>                                  <C>              <C>                   <C>            <C>
    Capital Appreciation Portfolio          0.65%            0.25%                0.04%              0.94%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of the Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolio with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in the Portfolio for the time
   periods indicated then redeem all of your shares at the end of those
   periods. The example also assumes that your investment has a 5% return
   each year, and that the Portfolio's operating expenses remain the same.
   Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Capital Appreciation Portfolio                                  $96       $300
</TABLE>

 4 Janus Aspen Series
<PAGE>
                                      Investment objective, principal investment
                                                 strategies and risks

          Capital Appreciation Portfolio has a similar investment objective and
          similar principal investment strategies to Janus Twenty Fund. Although
          it is anticipated that the Portfolio and Janus Twenty Fund will hold
          similar securities, differences in asset size, cash flow needs and
          other factors may result in differences in investment performance. The
          expenses of the Portfolio and Janus Twenty Fund are expected to
          differ. The variable contract owner will also bear various insurance
          related costs at the insurance company level. You should review the
          accompanying separate account prospectus for a summary of fees and
          expenses.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          This section takes a closer look at the investment objective of
          Capital Appreciation Portfolio, its principal investment strategies
          and certain risks of investing in Capital Appreciation Portfolio.
          Strategies and policies that are noted as "fundamental" cannot be
          changed without a shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 9-10 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

          Capital Appreciation Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential. The Portfolio may invest in companies of
          any size, from larger, well-established companies to smaller, emerging
          growth companies.

The following questions and answers are designed to help you better understand
Capital Appreciation Portfolio's principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          The Portfolio may invest substantially all of its assets in common
          stocks if the portfolio manager believes that common stocks will
          appreciate in value. The portfolio manager generally takes a "bottom
          up" approach to selecting companies. In other words, he seeks to
          identify individual companies with earnings growth potential that may
          not be recognized by the market at large. He makes this assessment by
          looking at companies one at a time, regardless of size, country of
          organization, place of principal business activity, or other similar
          selection criteria. Realization of income is not a significant
          consideration when choosing investments for the Portfolio. Income
          realized on the Portfolio's investments may be incidental to its
          objective.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio manager seeks companies that meet his
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolio may invest and the
          Portfolio may at times have significant foreign exposure.

              Investment objective, principal investment strategies and risks  5
<PAGE>

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. Although Capital Appreciation Portfolio does
          not emphasize companies of any particular size, a Portfolio with a
          larger asset base is more likely to invest in larger, more established
          issuers.

 6 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          In investing its portfolio assets, the Portfolio will follow the
          general policies listed below. The percentage limitations included in
          these policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if the Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When the portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he is otherwise unable
          to locate attractive investment opportunities, the Portfolio's cash or
          similar investments may increase. In other words, the Portfolio does
          not always stay fully invested in stocks and bonds. Cash or similar
          investments generally are a residual - they represent the assets that
          remain after the portfolio manager has committed available assets to
          desirable investment opportunities. However, the portfolio manager may
          also temporarily increase the Portfolio's cash position to protect its
          assets or maintain liquidity.

          When the Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          Capital Appreciation Portfolio invests primarily in domestic and
          foreign equity securities, which may include preferred stocks, common
          stocks, warrants and securities convertible into common or preferred
          stocks. The Portfolio may also invest to a lesser degree in other
          types of securities. These securities (which are described in the
          Glossary) may include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of the Portfolio's assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          The Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolio's Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolio may invest without limit in foreign equity and debt
          securities. The Portfolio may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United

              Investment objective, principal investment strategies and risks  7
<PAGE>

          States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

          SPECIAL SITUATIONS
          The Portfolio may invest in special situations. A special situation
          arises when, in the opinion of the Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. The Portfolio's performance
          could suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolio generally intends to purchase securities for long-term
          investment although, to a limited extent, the Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. The Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in the Portfolio's holdings whenever the
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in the Portfolio's
          performance.

 8 Janus Aspen Series
<PAGE>

RISKS FOR CAPITAL APPRECIATION PORTFOLIO

          Because the Portfolio may invest substantially all of its assets in
          common stocks, the main risk is the risk that the value of the stocks
          it holds might decrease in response to the activities of an individual
          company or in response to general market and/or economic conditions.
          If this occurs, the Portfolio's share price may also decrease. The
          Portfolio's performance may also be affected by risks specific to
          certain types of investments, such as foreign securities, derivative
          investments, non-investment grade debt securities, initial public
          offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in Capital Appreciation Portfolio.

1. THE PORTFOLIO MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF CAPITAL APPRECIATION PORTFOLIO AFFECT
   ITS RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of the Portfolio.

3. HOW COULD THE PORTFOLIO'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
   PERFORMANCE?

          The Portfolio may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolio's performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as the Portfolio holds a foreign security,
            its value will be affected by the value of the local currency
            relative to the U.S. dollar. When the Portfolio sells a foreign
            denominated security, its value may be worth less in U.S. dollars
            even if the security increases in value in its home country. U.S.
            dollar denominated securities of foreign issuers may also be
            affected by currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may

              Investment objective, principal investment strategies and risks  9
<PAGE>

            take over the assets or operations of a company or that the
            government may impose taxes or limits on the removal of the
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

2. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

3. HOW DOES THE PORTFOLIO TRY TO REDUCE RISK?

          The Portfolio may use futures, options, swaps and other derivative
          instruments to "hedge" or protect its portfolio from adverse movements
          in securities prices and interest rates. The Portfolio may also use a
          variety of currency hedging techniques, including forward currency
          contracts, to manage exchange rate risk. The portfolio manager
          believes the use of these instruments will benefit the Portfolio.
          However, the Portfolio's performance could be worse than if the
          Portfolio had not used such instruments if the portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 10 Janus Aspen Series
<PAGE>
                                                     Management of the portfolio

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to the Portfolio and is responsible for the
          day-to-day management of the investment portfolio and other business
          affairs of the Portfolio.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning the Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolio, and may be reimbursed by the Portfolio for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolio and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolio's Shares
          may perform certain administrative services relating to the Portfolio
          and Janus Capital or the Portfolio may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          The Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with the Portfolio
          spells out the management fee and other expenses that the Portfolio
          must pay. In addition, the Shares of the Portfolio incur expenses not
          assumed by Janus Capital, including the distribution fee, transfer
          agent and custodian fees and expenses, legal and auditing fees,
          printing and mailing costs of sending reports and other information to
          existing shareholders, and independent Trustees' fees and expenses.
          The Portfolio expects to pay Janus Capital a management fee equal to
          0.65% of daily net assets during the fiscal year ended December 31,
          2000. For the fiscal year ended December 31, 1999, the Portfolio paid
          Janus Capital a management fee equal to 0.75% of the Portfolio's
          average net assets. This rate is based on a higher fee rate that was
          previously in effect.

                                                 Management of the portfolio  11
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGER

SCOTT W. SCHOELZEL
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Capital
            Appreciation Portfolio, which he has managed since its inception.
            He is portfolio manager of Janus Twenty Fund, which he has
            managed since August 1997. He previously managed Janus Olympus
            Fund from its inception to August 1997. Mr. Schoelzel joined
            Janus Capital in January 1994. He holds a Bachelor of Arts in
            Business from Colorado College.

 12 Janus Aspen Series
<PAGE>
                                                               Other information

          CLASSES OF SHARES

          The Portfolio currently offers three classes of shares, one of which,
          the Service Shares, are offered pursuant to this prospectus. The
          Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of the
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of the Portfolio are
          offered only to qualified plans using plan service providers that are
          compensated for providing distribution and/or record keeping and other
          administrative services provided to plan participants. Because the
          expenses of each class may differ, the performance of each class is
          expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, the Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of the Portfolio. Under the
          terms of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolio does not currently anticipate any disadvantages to
          owners of variable insurance contracts because the Portfolio offers
          its shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in the Portfolio or substitute Shares of
          another Portfolio. If this occurs, the Portfolio may be forced to sell
          its securities at disadvantageous prices. In addition, the Trustees
          may refuse to sell Shares of the Portfolio to any separate account or
          qualified plan or may suspend or terminate the offering of the
          Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of the Portfolio's shareholders.
          It is possible that a qualified plan investing in the Portfolio could
          lose its qualified plan status under the Internal Revenue Code, which
          could have adverse tax consequences on insurance company separate
          accounts investing in the Shares. Janus Capital intends to monitor
          such qualified plans and the Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if a plan loses (or in the
          opinion of Janus Capital is at risk of losing) its qualified plan
          status.

                                                           Other information  13
<PAGE>

          DISTRIBUTION OF THE PORTFOLIO

          The Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

 14 Janus Aspen Series
<PAGE>
                                                         Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolio, the Internal Revenue Code requires
          the Portfolio to distribute net income and any net gains realized on
          its investments annually. The Portfolio's income from dividends and
          interest and any net realized short-term gains are paid to
          shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of the Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of the Portfolio will automatically be
          reinvested into additional Shares of the Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of the Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of the Portfolio's Shares. The Share price of the Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Capital Appreciation Portfolio declared a dividend in the amount of
          $0.25 per share. If the price of Capital Appreciation Portfolio's
          Shares was $10.00 on December 30, the share price on December 31 would
          be $9.75, barring market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolio may be purchased only through variable
          insurance contracts and qualified plans, it is anticipated that any
          income dividends or capital gains distributions made by the Shares of
          the Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIO

          Dividends, interest and some gains received by the Portfolio on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolio may from year to year make the election permitted
          under Section 853 of the Internal Revenue Code to pass through such
          taxes to shareholders as a foreign tax credit. If such election is not
          made, any foreign taxes paid or accrued will represent an expense to
          the Portfolio which will reduce its investment income.

          The Portfolio does not expect to pay any federal income or excise
          taxes because it intends to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of the Portfolio
          are sold in connection with variable insurance contracts, the
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  15
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIO DIRECTLY.
          SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE INSURANCE
          CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING INSURANCE
          COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. REFER TO THE
          PROSPECTUS FOR THE PARTICIPATING INSURANCE COMPANY'S SEPARATE ACCOUNT
          OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON PURCHASING OR SELLING OF
          VARIABLE INSURANCE CONTRACTS AND ON HOW TO SELECT THE PORTFOLIO AS AN
          INVESTMENT OPTION FOR A CONTRACT OR A QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by the Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolio are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent the Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolio does not price its shares, the NAV of the Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of the Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolio's behalf.

          The Portfolio does not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. The Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of the Portfolio. Although there is no present
          intention to do so, the Portfolio may discontinue sales of its shares
          if management and the Trustees believe that continued sales may
          adversely affect the Portfolio's ability to achieve its investment
          objective. If sales of the Portfolio's Shares are discontinued, it is
          expected that existing participants invested in the Portfolio would be
          permitted to continue to authorize investment in the Portfolio and to
          reinvest any dividends or capital gains distributions, absent highly
          unusual circumstances. The Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of the Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption

 16 Janus Aspen Series
<PAGE>

          proceeds will normally be wired the business day following receipt of
          the redemption order, but in no event later than seven days after
          receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage the Portfolio's investments. The
          Portfolio does not permit frequent trading or market timing. When
          market timing occurs, the Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm the Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash the Portfolio will have to invest. When
          in Janus Capital's opinion such activity would have a disruptive
          effect on portfolio management, the Portfolio reserves the right to
          refuse purchase orders and exchanges into the Portfolio by any person,
          group or commonly controlled account. The Portfolio may notify a
          market timer of rejection of a purchase or exchange order after the
          day the order is placed. If the Portfolio allows a market timer to
          trade Portfolio shares, it may require the market timer to enter into
          a written agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolio that they have
          authorized for investment. Each report will show the investments owned
          by the Portfolio and the market values thereof, as well as other
          information about the Portfolio and its operations. The Trust's fiscal
          year ends December 31.

                                                         Shareholder's guide  17
<PAGE>
Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

 18 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolio may
          invest. The Portfolio may invest in these instruments to the extent
          permitted by its investment objective and policies. The Portfolio is
          not limited by this discussion and may invest in any other types of
          instruments not precluded by the policies discussed elsewhere in this
          Prospectus. Please refer to the SAI for a more detailed discussion of
          certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolio may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, the portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  19
<PAGE>

          Portfolio must pay if these investments are profitable, the Portfolio
          may make various elections permitted by the tax laws. These elections
          could require that the Portfolio recognize taxable income, which in
          turn must be distributed, before the securities are sold and before
          cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by the
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, the Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by the
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by the Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 20 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolio
          does not earn interest on such securities until settlement and bear
          the risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolio may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. It may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolio may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolio may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          The Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  21
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolio may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 22 Janus Aspen Series
<PAGE>

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<PAGE>

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<PAGE>

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<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolio.

The Statement of Additional Information provides detailed
information about the Portfolio and is incorporated into this
Prospectus by reference. You may review the Portfolio's Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>

                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Balanced Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                Balanced Portfolio (the "Portfolio") is a mutual fund in Janus
                Aspen Series and is described in this prospectus. The Portfolio
                currently offers three classes of shares. The Service Shares,
                (the "Shares"), are offered by this prospectus in connection
                with investment in and payments under variable annuity contracts
                and variable life insurance contracts (collectively, "variable
                insurance contracts"), as well as certain qualified retirement
                plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. See the accompanying
                contract prospectus for information regarding contract fees and
                expenses and any restrictions on purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolio.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Balanced Portfolio.......................................    2
                   Fees and expenses........................................    4
                INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Balanced Portfolio.......................................    5
                   General portfolio policies...............................    7
                   Risks for Balanced Portfolio.............................    9
                MANAGEMENT OF THE PORTFOLIO
                   Investment adviser.......................................   11
                   Management expenses and expense limits...................   11
                   Investment personnel.....................................   12
                OTHER INFORMATION...........................................   13
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   15
                   Taxes....................................................   15
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   16
                   Purchases................................................   16
                   Redemptions..............................................   16
                   Frequent trading.........................................   17
                   Shareholder communications...............................   17
                FINANCIAL HIGHLIGHTS........................................   18
                GLOSSARY
                   Glossary of investment terms.............................   19

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

BALANCED PORTFOLIO

          Balanced Portfolio is designed for long-term investors who seek growth
          of capital and who can tolerate the greater risks associated with
          common stock investments.

1. WHAT IS THE INVESTMENT OBJECTIVE OF BALANCED PORTFOLIO?

- --------------------------------------------------------------------------------

          - BALANCED PORTFOLIO seeks long-term capital growth, consistent
            with preservation of capital and balanced by current income.

          The Portfolio's Trustees may change this objective without a
          shareholder vote and the Portfolio will notify you of any changes that
          are material. If there is a material change to the Portfolio's
          objective or policies, you should consider whether the Portfolio
          remains an appropriate investment for you. There is no guarantee that
          the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF BALANCED PORTFOLIO?

          The portfolio manager applies a "bottom up" approach in choosing
          investments. In other words, she looks for companies with earnings
          growth potential one at a time. If the portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of the Portfolio's assets may be in cash or similar investments.

          Balanced Portfolio normally invests 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. The
          Portfolio will normally invest at least 25% of its assets in
          fixed-income securities.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN BALANCED PORTFOLIO?

          The biggest risk of investing in this Portfolio is that its returns
          may vary, and you could lose money. If you are considering investing
          in Balanced Portfolio, remember that it is designed for long-term
          investors who can accept the risks of investing in a portfolio with
          significant common stock holdings. Common stocks tend to be more
          volatile than other investment choices.

          The value of the Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of the
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of the Portfolio's holdings decreases, the
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in the Portfolio you would get back less money.

          The income component of Balanced Portfolio includes fixed-income
          securities. A fundamental risk to the income component is that the
          value of these securities will fall if interest rates rise. Generally,
          the value of a fixed-income portfolio will decrease when interest
          rates rise, which means the Portfolio's NAV may likewise decrease.
          Another fundamental risk associated with fixed-income securities is
          credit risk, which is the risk that an issuer of a bond will be unable
          to make principal and interest payments when due.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in Balanced Portfolio by showing how Balanced Portfolio's
          performance has varied over time. The Portfolio's Service Shares
          commenced operations on December 31, 1999. The returns shown for the
          Service Shares of the Portfolio reflect the historical performance of
          a different class of shares (the Institutional Shares) prior to
          December 31, 1999, restated based on the Service Shares' estimated
          fees and expenses (ignoring any fee

 2 Janus Aspen Series
<PAGE>

          and expense limitations). The bar chart depicts the change in
          performance from year-to-year during the period indicated but does not
          include charges and expenses attributable to any insurance product
          which would lower the performance illustrated. The Portfolio does not
          impose any sales or other charges that would affect total return
          computations. Total return figures include the effect of the
          Portfolio's expenses. The table compares the average annual returns
          for the Service Shares of the Portfolio for the periods indicated to a
          broad-based securities market index.

           BALANCED PORTFOLIO

          Annual return for periods ended 12/31

                             0.84%    24.79%   16.18%   21.96%   34.03%   26.03%
                              1994     1995     1996     1997     1998     1999

          Best Quarter:   4th-1998  20.26%    Worst Quarter:   3rd-1998  (5.02%)

                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Balanced Portfolio                                        26.03%    24.55%         20.51%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                Lehman Brothers Gov't/Corp Bond Index**                   (2.15%)    7.61%          5.40%
                                                                      --------------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

          ** Lehman Brothers Gov't/Corp Bond Index is composed of all bonds that
             are of investment grade with at least one year until maturity.

          Balanced Portfolio's past performance does not necessarily indicate
          how it will perform in the future.

                                                          Risk return summary  3
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolio. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of the Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolio in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.

<TABLE>
<CAPTION>
                                               Distribution                    Total Annual
                             Management           (12b-1)         Other       Fund Operating
                                 Fee              Fees(1)       Expenses        Expenses(2)
    <S>                      <C>               <C>              <C>           <C>
    Balanced Portfolio         0.65%              0.25%           0.02%           0.92%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of the Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolio with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in the Portfolio for the time
   periods indicated then redeem all of your shares at the end of those
   periods. The example also assumes that your investment has a 5% return
   each year, and that the Portfolio's operating expenses remain the same.
   Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Balanced Portfolio                                             $ 94       $293
</TABLE>

 4 Janus Aspen Series
<PAGE>
                                      Investment objective, principal investment
                                                 strategies and risks

          Balanced Portfolio has a similar investment objective and similar
          principal investment strategies to Janus Balanced Fund. Although it is
          anticipated that the Portfolio and Janus Balanced Fund will hold
          similar securities, differences in asset size, cash flow needs and
          other factors may result in differences in investment performance. The
          expenses of the Portfolio and Janus Balanced Fund are expected to
          differ. The variable contract owner will also bear various insurance
          related costs at the insurance company level. You should review the
          accompanying separate account prospectus for a summary of fees and
          expenses.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          This section takes a closer look at the investment objective of
          Balanced Portfolio, its principal investment strategies and certain
          risks of investing in Balanced Portfolio. Strategies and policies that
          are noted as "fundamental" cannot be changed without a shareholder
          vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 9-10 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

          Balanced Portfolio seeks long-term capital growth, consistent with
          preservation of capital and balanced by current income. It pursues its
          objective by normally investing 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. This
          Portfolio normally invests at least 25% of its assets in fixed-income
          securities.

The following questions and answers are designed to help you better understand
Balanced Portfolio's principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          The Portfolio may invest substantially all of its assets in common
          stocks if the portfolio manager believes that common stocks will
          appreciate in value. The portfolio manager generally takes a "bottom
          up" approach to selecting companies. In other words, she seeks to
          identify individual companies with earnings growth potential that may
          not be recognized by the market at large. She makes this assessment by
          looking at companies one at a time, regardless of size, country of
          organization, place of principal business activity, or other similar
          selection criteria. The portfolio manager may consider dividend-paying
          characteristics to a greater degree in selecting common stock.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio manager seeks companies that meet her
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolio may invest and the
          Portfolio may at times have significant foreign exposure.

              Investment objective, principal investment strategies and risks  5
<PAGE>

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. Although Balanced Portfolio does not emphasize
          companies of any particular size, a Portfolio with a larger asset base
          are more likely to invest in larger, more established issuers.

4. HOW ARE ASSETS ALLOCATED BETWEEN THE GROWTH AND INCOME COMPONENTS OF BALANCED
   PORTFOLIO'S HOLDINGS?

          Balanced Portfolio shifts assets between the growth and income
          components of its holdings based on the portfolio manager's analysis
          of relevant market, financial and economic conditions. If the
          portfolio manager believes that growth securities will provide better
          returns than the yields then available or expected on income-producing
          securities, the Portfolio will place a greater emphasis on the growth
          component.

5. WHAT TYPES OF SECURITIES MAKE UP THE GROWTH COMPONENT OF THE BALANCED
   PORTFOLIO'S INVESTMENTS?

          The growth component of the Portfolio is expected to consist primarily
          of common stocks, but may also include warrants, preferred stocks or
          convertible securities selected primarily for their growth potential.

6. WHAT TYPES OF SECURITIES MAKE UP THE INCOME COMPONENT OF BALANCED PORTFOLIO'S
   HOLDINGS?

          The income component of Balanced Portfolio is expected to consist of
          securities that the portfolio manager believes have income potential.
          Such securities may include equity securities, convertible securities
          and all types of debt securities. Equity securities may be included in
          the income component of the Portfolio if they currently pay dividends
          or the portfolio manager believes they have the potential for either
          increasing their dividends or commencing dividends, if none are
          currently paid.

7. HOW DO INTEREST RATES AFFECT THE VALUE OF MY INVESTMENT?

          Generally, a fixed-income security will increase in value when
          interest rates fall and decrease in value when interest rates rise.
          Longer-term securities are generally more sensitive to interest rate
          changes than shorter-term securities, but they generally offer higher
          yields to compensate investors for the associated risks. High-yield
          bond prices are generally less directly responsive to interest rate
          changes than investment grade issues and may not always follow this
          pattern. A bond fund's average-weighted effective maturity and its
          duration are measures of how the fund may react to interest rate
          changes.

 6 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          In investing its portfolio assets, the Portfolio will follow the
          general policies listed below. The percentage limitations included in
          these policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if the Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When the portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when she is otherwise unable
          to locate attractive investment opportunities, the Portfolio's cash or
          similar investments may increase. In other words, the Portfolio does
          not always stay fully invested in stocks and bonds. Cash or similar
          investments generally are a residual - they represent the assets that
          remain after the portfolio manager has committed available assets to
          desirable investment opportunities. However, the portfolio manager may
          also temporarily increase the Portfolio's cash position to protect its
          assets or maintain liquidity.

          When the Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          Balanced Portfolio invests primarily in domestic and foreign equity
          securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Portfolio may also invest to a lesser degree in other types of
          securities. These securities (which are described in the Glossary) may
          include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of the Portfolio's assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          The Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolio's Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolio may invest without limit in foreign equity and debt
          securities. The Portfolio may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

              Investment objective, principal investment strategies and risks  7
<PAGE>

          SPECIAL SITUATIONS
          The Portfolio may invest in special situations. A special situation
          arises when, in the opinion of the Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. The Portfolio's performance
          could suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolio generally intends to purchase securities for long-term
          investment although, to a limited extent, the Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. The Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in the Portfolio's holdings whenever the
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in the Portfolio's
          performance.

 8 Janus Aspen Series
<PAGE>

RISKS FOR BALANCED PORTFOLIO

          Because the Portfolio may invest substantially all of its assets in
          common stocks, the main risk is the risk that the value of the stocks
          it holds might decrease in response to the activities of an individual
          company or in response to general market and/or economic conditions.
          If this occurs, the Portfolio's share price may also decrease. The
          Portfolio's performance may also be affected by risks specific to
          certain types of investments, such as foreign securities, derivative
          investments, non-investment grade bonds, initial public offerings
          (IPOs) or companies with relatively small market capitalizations. IPOs
          and other investment techniques may have a magnified performance
          impact on a portfolio with a small asset base. A portfolio may not
          experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in Balanced Portfolio.

1. THE PORTFOLIO MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW COULD THE PORTFOLIO'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
   PERFORMANCE?

          The Portfolio may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolio's performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as the Portfolio holds a foreign security,
            its value will be affected by the value of the local currency
            relative to the U.S. dollar. When the Portfolio sells a foreign
            denominated security, its value may be worth less in U.S. dollars
            even if the security increases in value in its home country. U.S.
            dollar denominated securities of foreign issuers may also be
            affected by currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may take over the assets or operations of a company or
            that the government may impose taxes or limits on the removal of the
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

              Investment objective, principal investment strategies and risks  9
<PAGE>

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

3. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade bonds. Issuers
          of high-yield bonds may not be as strong financially as those issuing
          bonds with higher credit ratings and are more vulnerable to real or
          perceived economic changes, political changes or adverse developments
          specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

4. HOW DOES THE PORTFOLIO TRY TO REDUCE RISK?

          The Portfolio may use futures, options, swaps and other derivative
          instruments to "hedge" or protect its portfolio from adverse movements
          in securities prices and interest rates. The Portfolio may also use a
          variety of currency hedging techniques, including forward currency
          contracts, to manage exchange rate risk. The portfolio manager
          believes the use of these instruments will benefit the Portfolio.
          However, the Portfolio's performance could be worse than if the
          Portfolio had not used such instruments if the portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 10 Janus Aspen Series
<PAGE>
                                                     Management of the portfolio

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to the Portfolio and is responsible for the
          day-to-day management of the investment portfolio and other business
          affairs of the Portfolio.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning the Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolio, and may be reimbursed by the Portfolio for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolio and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolio's Shares
          may perform certain administrative services relating to the Portfolio
          and Janus Capital or the Portfolio may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          The Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with the Portfolio
          spells out the management fee and other expenses that the Portfolio
          must pay. In addition, the Shares of the Portfolio incur expenses not
          assumed by Janus Capital, including the distribution fee, transfer
          agent and custodian fees and expenses, legal and auditing fees,
          printing and mailing costs of sending reports and other information to
          existing shareholders, and independent Trustees' fees and expenses.
          The Portfolio expects to pay Janus Capital a management fee equal to
          0.65% of average daily net assets during the fiscal year ended
          December 31, 2000. For the fiscal year ended December 31, 1999, the
          Portfolio paid Janus Capital a management fee equal to 0.67% of the
          Portfolio's average net assets. This rate is based on a higher fee
          rate that was previously in effect.

                                                 Management of the portfolio  11
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGER

KAREN L. REIDY
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Balanced
            Portfolio and Equity Income Portfolio as of January 2000, and an
            assistant portfolio manager of Growth Portfolio since 1998. She
            also manages Janus Balanced Fund and Janus Equity Income Fund as
            of January 2000. She is also assistant portfolio manager of Janus
            Fund. Prior to joining Janus Capital in 1995, she worked for
            Price Waterhouse as a manager in both the Mergers and
            Acquisitions and Audit business units. In this capacity, Ms.
            Reidy performed due diligence work for corporate clients and
            oversaw audit engagements. She received an undergraduate degree
            in Accounting from the University of Colorado in 1989 and passed
            the CPA exam in 1992. She has earned the right to use the
            Chartered Financial Analyst designation.

 12 Janus Aspen Series
<PAGE>
                                                               Other information

          CLASSES OF SHARES

          The Portfolio currently offers three classes of shares, one of which,
          the Service Shares, are offered pursuant to this prospectus. The
          Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of the
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of the Portfolio are
          offered only to qualified plans using plan service providers that are
          compensated for providing distribution and/or record keeping and other
          administrative services provided to plan participants. Because the
          expenses of each class may differ, the performance of each class is
          expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, the Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of the Portfolio. Under the
          terms of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolio does not currently anticipate any disadvantages to
          owners of variable insurance contracts because the Portfolio offers
          its shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in the Portfolio or substitute Shares of
          another Portfolio. If this occurs, the Portfolio may be forced to sell
          its securities at disadvantageous prices. In addition, the Trustees
          may refuse to sell Shares of the Portfolio to any separate account or
          qualified plan or may suspend or terminate the offering of the
          Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of the Portfolio's shareholders.
          It is possible that a qualified plan investing in the Portfolio could
          lose its qualified plan status under the Internal Revenue Code, which
          could have adverse tax consequences on insurance company separate
          accounts investing in the Shares. Janus Capital intends to monitor
          such qualified plans and the Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if a plan loses (or in the
          opinion of Janus Capital is at risk of losing) its qualified plan
          status.

                                                           Other information  13
<PAGE>

          DISTRIBUTION OF THE PORTFOLIO

          The Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

 14 Janus Aspen Series
<PAGE>
                                                         Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolio, the Internal Revenue Code requires
          the Portfolio to distribute net income and any net gains realized on
          its investments annually. The Portfolio's income from dividends and
          interest and any net realized short-term gains are paid to
          shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of the Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of the Portfolio will automatically be
          reinvested into additional Shares of the Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of the Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of the Portfolio's Shares. The Share price of the Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Balanced Portfolio declared a dividend in the amount of $0.25 per
          share. If the price of Balanced Portfolio's Shares was $10.00 on
          December 30, the share price on December 31 would be $9.75, barring
          market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolio may be purchased only through variable
          insurance contracts and qualified plans, it is anticipated that any
          income dividends or capital gains distributions made by the Shares of
          the Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIO

          Dividends, interest and some gains received by the Portfolio on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolio may from year to year make the election permitted
          under Section 853 of the Internal Revenue Code to pass through such
          taxes to shareholders as a foreign tax credit. If such election is not
          made, any foreign taxes paid or accrued will represent an expense to
          the Portfolio which will reduce its investment income.

          The Portfolio does not expect to pay any federal income or excise
          taxes because it intends to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of the Portfolio
          are sold in connection with variable insurance contracts, the
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  15
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIO DIRECTLY.
          SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE INSURANCE
          CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING INSURANCE
          COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. REFER TO THE
          PROSPECTUS FOR THE PARTICIPATING INSURANCE COMPANY'S SEPARATE ACCOUNT
          OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON PURCHASING OR SELLING OF
          VARIABLE INSURANCE CONTRACTS AND ON HOW TO SELECT THE PORTFOLIO AS AN
          INVESTMENT OPTION FOR A CONTRACT OR A QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by the Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolio are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent the Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolio does not price its shares, the NAV of the Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of the Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolio's behalf.

          The Portfolio does not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. The Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of the Portfolio. Although there is no present
          intention to do so, the Portfolio may discontinue sales of its shares
          if management and the Trustees believe that continued sales may
          adversely affect the Portfolio's ability to achieve its investment
          objective. If sales of the Portfolio's Shares are discontinued, it is
          expected that existing participants invested in the Portfolio would be
          permitted to continue to authorize investment in the Portfolio and to
          reinvest any dividends or capital gains distributions, absent highly
          unusual circumstances. The Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of the Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption

 16 Janus Aspen Series
<PAGE>

          proceeds will normally be wired the business day following receipt of
          the redemption order, but in no event later than seven days after
          receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage the Portfolio's investments. The
          Portfolio does not permit frequent trading or market timing. When
          market timing occurs, the Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm the Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash the Portfolio will have to invest. When
          in Janus Capital's opinion such activity would have a disruptive
          effect on portfolio management, the Portfolio reserves the right to
          refuse purchase orders and exchanges into the Portfolio by any person,
          group or commonly controlled account. The Portfolio may notify a
          market timer of rejection of a purchase or exchange order after the
          day the order is placed. If the Portfolio allows a market timer to
          trade Portfolio shares, it may require the market timer to enter into
          a written agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolio that they have
          authorized for investment. Each report will show the investments owned
          by the Portfolio and the market values thereof, as well as other
          information about the Portfolio and its operations. The Trust's fiscal
          year ends December 31.

                                                         Shareholder's guide  17
<PAGE>
Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

 18 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolio may
          invest. The Portfolio may invest in these instruments to the extent
          permitted by its investment objective and policies. The Portfolio is
          not limited by this discussion and may invest in any other types of
          instruments not precluded by the policies discussed elsewhere in this
          Prospectus. Please refer to the SAI for a more detailed discussion of
          certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolio may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, the portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  19
<PAGE>

          Portfolio must pay if these investments are profitable, the Portfolio
          may make various elections permitted by the tax laws. These elections
          could require that the Portfolio recognize taxable income, which in
          turn must be distributed, before the securities are sold and before
          cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by the
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, the Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by the
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by the Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 20 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolio
          does not earn interest on such securities until settlement and bear
          the risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolio may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. It may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolio may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolio may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          The Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  21
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolio may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 22 Janus Aspen Series
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolio.

The Statement of Additional Information provides detailed
information about the Portfolio and is incorporated into this
Prospectus by reference. You may review and copy information about
the Portfolio (including the Portfolio's Statement of Additional
Information) at the Public Reference Room of the SEC or get text
only copies, after paying a duplicating fee, by sending an
electronic request by e-mail to [email protected] or by writing to
or calling the Public Reference Room, Washington, D.C. 20549-0102
(1-202-942-8090). You may also obtain reports and other information
about the Portfolio from the Electronic Data Gathering Analysis and
Retrieval (EDGAR) Database on the SEC's Web site at
http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>

                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Growth and Income Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                Growth and Income Portfolio (the "Portfolio") is a mutual fund
                in Janus Aspen Series and is described in this prospectus. The
                Portfolio currently offers three classes of shares. The Service
                Shares, (the "Shares"), are offered by this prospectus in
                connection with investment in and payments under variable
                annuity contracts and variable life insurance contracts
                (collectively, "variable insurance contracts"), as well as
                certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. See the accompanying
                contract prospectus for information regarding contract fees and
                expenses and any restrictions on purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolio.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Growth and Income Portfolio..............................    2
                   Fees and expenses........................................    4
                INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Growth and Income Portfolio..............................    5
                   General portfolio policies...............................    7
                   Risks for Growth and Income Portfolio....................    9
                MANAGEMENT OF THE PORTFOLIO
                   Investment adviser.......................................   11
                   Management expenses and expense limits...................   11
                   Investment personnel.....................................   12
                OTHER INFORMATION...........................................   13
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   15
                   Taxes....................................................   15
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   16
                   Purchases................................................   16
                   Redemptions..............................................   16
                   Frequent trading.........................................   17
                   Shareholder communications...............................   17
                FINANCIAL HIGHLIGHTS........................................   18
                GLOSSARY
                   Glossary of investment terms.............................   19

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

GROWTH AND INCOME PORTFOLIO

          Growth and Income Portfolio is designed for long-term investors who
          seek growth of capital and who can tolerate the greater risks
          associated with common stock investments.

1. WHAT IS THE INVESTMENT OBJECTIVE OF GROWTH AND INCOME PORTFOLIO?

- --------------------------------------------------------------------------------

          - GROWTH AND INCOME PORTFOLIO seeks long-term capital growth and
            current income.

          The Portfolio's Trustees may change this objective without a
          shareholder vote and the Portfolio will notify you of any changes that
          are material. If there is a material change to the Portfolio's
          objective or policies, you should consider whether the Portfolio
          remains an appropriate investment for you. There is no guarantee that
          the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF GROWTH AND INCOME PORTFOLIO?

          The portfolio manager applies a "bottom up" approach in choosing
          investments. In other words, he looks for companies with earnings
          growth potential one at a time. If the portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of the Portfolio's assets may be in cash or similar investments.

          Growth and Income Portfolio normally emphasizes investments in common
          stocks. It will normally invest up to 75% of its assets in equity
          securities selected primarily for their growth potential, and at least
          25% of its assets in securities the portfolio manager believes have
          income potential. Equity securities may make up part of this income
          component if they currently pay dividends or the portfolio manager
          believes they have potential for increasing or commencing dividend
          payments.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN GROWTH AND INCOME PORTFOLIO?

          The biggest risk of investing in this Portfolio is that its returns
          may vary, and you could lose money. If you are considering investing
          in Growth and Income Portfolio, remember that it is designed for
          long-term investors who can accept the risks of investing in a
          portfolio with significant common stock holdings. Common stocks tend
          to be more volatile than other investment choices.

          The value of the Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of the
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of the Portfolio's holdings decreases, the
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in the Portfolio you would get back less money.

          The income component of Growth and Income Portfolio includes
          fixed-income securities. A fundamental risk to the income component is
          that the value of these securities will fall if interest rates rise.
          Generally, the value of a fixed-income portfolio will decrease when
          interest rates rise, which means the Portfolio's NAV may likewise
          decrease. Another fundamental risk associated with fixed-income
          securities is credit risk, which is the risk that an issuer of a bond
          will be unable to make principal and interest payments when due.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in Growth and Income Portfolio by showing how Growth and
          Income Portfolio's performance has varied over time. The Portfolio's
          Service Shares commenced operations on December 31, 1999. The returns
          shown for the Service Shares of

 2 Janus Aspen Series
<PAGE>

          the Portfolio reflect the historical performance of a different class
          of shares (the Institutional Shares) prior to December 31, 1999,
          restated based on the Service Shares' estimated fees and expenses
          (ignoring any fee and expense limitations). The bar chart depicts the
          change in performance from year-to-year during the period indicated
          but does not include charges and expenses attributable to any
          insurance product which would lower the performance illustrated. The
          Portfolio does not impose any sales or other charges that would affect
          total return computations. Total return figures include the effect of
          the Portfolio's expenses. The table compares the average annual
          returns for the Service Shares of the Portfolio for the periods
          indicated to a broad-based securities market index.

           GROWTH AND INCOME PORTFOLIO

          Annual returns for periods ended 12/31

                                                                          73.09%
                                                                           1999

          Best Quarter:  4th 1999  37.51%         Worst Quarter: 3rd-1999  4.30%

                           Average annual total return for period ended 12/31/99
                           -----------------------------------------------------

<TABLE>
<CAPTION>
                                                                                           Since Inception
                                                                                 1 year       (5/1/98)
                <S>                                                              <C>       <C>
                Growth and Income Portfolio                                      73.09%        54.92%
                S&P 500 Index*                                                   21.03%        19.85%
                                                                             --------------------------------
</TABLE>

          * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
            a widely recognized, unmanaged index of common stock prices.

          Growth and Income Portfolio's past performance does not necessarily
          indicate how it will perform in the future.

                                                          Risk return summary  3
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolio. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of the Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolio in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.

<TABLE>
<CAPTION>
                                                        Distribution                    Total Annual Fund
                                      Management           (12b-1)          Other          Operating
                                          Fee              Fees(1)         Expenses        Expenses(2)
    <S>                               <C>                <C>               <C>          <C>
    Growth and Income Portfolio          0.65%              0.25%           0.40%            1.30%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of the Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolio with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in the Portfolio for the time
   periods indicated then redeem all of your shares at the end of those
   periods. The example also assumes that your investment has a 5% return
   each year, and that the Portfolio's operating expenses remain the same.
   Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Growth and Income Portfolio                                    $132      $  412
</TABLE>

 4 Janus Aspen Series
<PAGE>
                                      Investment objective, principal investment
                                                 strategies and risks

          Growth and Income Portfolio has a similar investment objective and
          similar principal investment strategies to Janus Growth and Income
          Fund. Although it is anticipated that the Portfolio and Janus Growth
          and Income Fund will hold similar securities, differences in asset
          size, cash flow needs and other factors may result in differences in
          investment performance. The expenses of the Portfolio and Janus Growth
          and Income Fund are expected to differ. The variable contract owner
          will also bear various insurance related costs at the insurance
          company level. You should review the accompanying separate account
          prospectus for a summary of fees and expenses.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          This section takes a closer look at the investment objective of Growth
          and Income Portfolio, its principal investment strategies and certain
          risks of investing in Growth and Income Portfolio. Strategies and
          policies that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 9-10 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

          Growth and Income Portfolio seeks long-term capital growth and current
          income. It normally emphasizes investments in common stocks. It will
          normally invest up to 75% of its assets in equity securities selected
          primarily for their growth potential, and at least 25% of its assets
          in securities the portfolio manager believes have income potential.
          Because of this investment strategy, the Portfolio is not designed for
          investors who need consistent income.

The following questions and answers are designed to help you better understand
Growth and Income Portfolio's principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          The Portfolio may invest substantially all of its assets in common
          stocks if the portfolio manager believes that common stocks will
          appreciate in value. The portfolio manager generally takes a "bottom
          up" approach to selecting companies. In other words, he seeks to
          identify individual companies with earnings growth potential that may
          not be recognized by the market at large. He makes this assessment by
          looking at companies one at a time, regardless of size, country of
          organization, place of principal business activity, or other similar
          selection criteria. The portfolio manager may consider dividend-paying
          characteristics to a greater degree in selecting common stock.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio manager seeks companies that meet his
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolio may invest and the
          Portfolio may at times have significant foreign exposure.

              Investment objective, principal investment strategies and risks  5
<PAGE>

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. Although Growth and Income Portfolio does not
          emphasize companies of any particular size, a Portfolio with a larger
          asset base are more likely to invest in larger, more established
          issuers.

4. HOW ARE ASSETS ALLOCATED BETWEEN THE GROWTH AND INCOME COMPONENTS OF GROWTH
   AND INCOME PORTFOLIO'S HOLDINGS?

          Growth and Income Portfolio shifts assets between the growth and
          income components of its holdings based on the portfolio manager's
          analysis of relevant market, financial and economic conditions. If the
          portfolio manager believes that growth securities will provide better
          returns than the yields then available or expected on income-producing
          securities, the Portfolio will place a greater emphasis on the growth
          component.

5. WHAT TYPES OF SECURITIES MAKE UP THE GROWTH COMPONENT OF GROWTH AND INCOME
   PORTFOLIO?

          The growth component of the Portfolio is expected to consist primarily
          of common stocks, but may also include warrants, preferred stocks or
          convertible securities selected primarily for their growth potential.

6. WHAT TYPES OF SECURITIES MAKE UP THE INCOME COMPONENT OF GROWTH AND INCOME
   PORTFOLIO'S HOLDINGS?

          The income component of Growth and Income Portfolio is expected to
          consist of securities that the portfolio manager believes have income
          potential. Such securities may include equity securities, convertible
          securities and all types of debt securities. Equity securities may be
          included in the income component of the Portfolio if they currently
          pay dividends or the portfolio manager believes they have the
          potential for either increasing their dividends or commencing
          dividends, if none are currently paid.

7. HOW DO INTEREST RATES AFFECT THE VALUE OF MY INVESTMENT?

          Generally, a fixed-income security will increase in value when
          interest rates fall and decrease in value when interest rates rise.
          Longer-term securities are generally more sensitive to interest rate
          changes than shorter-term securities, but they generally offer higher
          yields to compensate investors for the associated risks. High-yield
          bond prices are generally less directly responsive to interest rate
          changes than investment grade issues and may not always follow this
          pattern. A bond fund's average-weighted effective maturity and its
          duration are measures of how the fund may react to interest rate
          changes.

 6 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          In investing its portfolio assets, the Portfolio will follow the
          general policies listed below. The percentage limitations included in
          these policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if the Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When the portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he is otherwise unable
          to locate attractive investment opportunities, the Portfolio's cash or
          similar investments may increase. In other words, the Portfolio does
          not always stay fully invested in stocks and bonds. Cash or similar
          investments generally are a residual - they represent the assets that
          remain after a portfolio manager has committed available assets to
          desirable investment opportunities. However, the portfolio manager may
          also temporarily increase the Portfolio's cash position to protect its
          assets or maintain liquidity.

          When the Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          Growth and Income Portfolio invests primarily in domestic and foreign
          equity securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Portfolio may also invest to a lesser degree in other types of
          securities. These securities (which are described in the Glossary) may
          include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of the Portfolio's assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          The Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolio's Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolio may invest without limit in foreign equity and debt
          securities. The Portfolio may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

              Investment objective, principal investment strategies and risks  7
<PAGE>

          SPECIAL SITUATIONS
          The Portfolio may invest in special situations. A special situation
          arises when, in the opinion of the Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. The Portfolio's performance
          could suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolio generally intends to purchase securities for long-term
          investment although, to a limited extent, the Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. The Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in the Portfolio's holdings whenever the
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in the Portfolio's
          performance.

 8 Janus Aspen Series
<PAGE>

RISKS FOR GROWTH AND INCOME PORTFOLIO

          Because the Portfolio may invest substantially all of its assets in
          common stocks, the main risk is the risk that the value of the stocks
          it holds might decrease in response to the activities of an individual
          company or in response to general market and/or economic conditions.
          If this occurs, the Portfolio's share price may also decrease. The
          Portfolio's performance may also be affected by risks specific to
          certain types of investments, such as foreign securities, derivative
          investments, non-investment grade bonds, initial public offerings
          (IPOs) or companies with relatively small market capitalizations. IPOs
          and other investment techniques may have a magnified performance
          impact on a portfolio with a small asset base. A portfolio may not
          experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in Growth and Income Portfolio.

1. THE PORTFOLIO MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW COULD THE PORTFOLIO'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
   PERFORMANCE?

          The Portfolio may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolio's performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as the Portfolio holds a foreign security,
            its value will be affected by the value of the local currency
            relative to the U.S. dollar. When the Portfolio sells a foreign
            denominated security, its value may be worth less in U.S. dollars
            even if the security increases in value in its home country. U.S.
            dollar denominated securities of foreign issuers may also be
            affected by currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may take over the assets or operations of a company or
            that the government may impose taxes or limits on the removal of the
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

              Investment objective, principal investment strategies and risks  9
<PAGE>

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

3. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade bonds. Issuers
          of high-yield bonds may not be as strong financially as those issuing
          bonds with higher credit ratings and are more vulnerable to real or
          perceived economic changes, political changes or adverse developments
          specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

4. HOW DOES THE PORTFOLIO TRY TO REDUCE RISK?

          The Portfolio may use futures, options, swaps and other derivative
          instruments to "hedge" or protect its portfolio from adverse movements
          in securities prices and interest rates. The Portfolio may also use a
          variety of currency hedging techniques, including forward currency
          contracts, to manage exchange rate risk. The portfolio manager
          believes the use of these instruments will benefit the Portfolio.
          However, the Portfolio's performance could be worse than if the
          Portfolio had not used such instruments if the portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 10 Janus Aspen Series
<PAGE>
                                                     Management of the portfolio

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to the Portfolio and is responsible for the
          day-to-day management of the investment portfolio and other business
          affairs of the Portfolio.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning the Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolio, and may be reimbursed by the Portfolio for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolio and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolio's Shares
          may perform certain administrative services relating to the Portfolio
          and Janus Capital or the Portfolio may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          The Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with the Portfolio
          spells out the management fee and other expenses that the Portfolio
          must pay. In addition, the Shares of the Portfolio incur expenses not
          assumed by Janus Capital, including the distribution fee, transfer
          agent and custodian fees and expenses, legal and auditing fees,
          printing and mailing costs of sending reports and other information to
          existing shareholders, and independent Trustees' fees and expenses.
          The Portfolio expects to pay Janus Capital a management fee equal to
          0.65% of average daily net assets during the fiscal year ended
          December 31, 2000. For the fiscal year ended December 31, 1999, the
          Portfolio paid Janus Capital a management fee equal to 0.75% of the
          Portfolio's average net assets. This rate is based on a higher fee
          rate that was previously in effect.

                                                 Management of the portfolio  11
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGER

DAVID J. CORKINS
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Growth and
            Income Portfolio which he has managed since its inception. He is
            Executive Vice President and portfolio manager of Janus Growth
            and Income Fund which he has managed since August 1997. He is an
            assistant portfolio manager of Janus Mercury Fund. He joined
            Janus in 1995 as a research analyst specializing in domestic
            financial services companies and a variety of foreign industries.
            Prior to joining Janus, he was the Chief Financial Officer of
            Chase U.S. Consumer Services, Inc., a Chase Manhattan mortgage
            business. He holds a Bachelor of Arts in English and Russian from
            Dartmouth and received his Master of Business Administration from
            Columbia University in 1993.

 12 Janus Aspen Series
<PAGE>
                                                               Other information

          CLASSES OF SHARES

          The Portfolio currently offers three classes of shares, one of which,
          the Service Shares, are offered pursuant to this prospectus. The
          Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of the
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of the Portfolio are
          offered only to qualified plans using plan service providers that are
          compensated for providing distribution and/or record keeping and other
          administrative services provided to plan participants. Because the
          expenses of each class may differ, the performance of each class is
          expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, the Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of the Portfolio. Under the
          terms of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolio does not currently anticipate any disadvantages to
          owners of variable insurance contracts because the Portfolio offers
          its shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in the Portfolio or substitute Shares of
          another Portfolio. If this occurs, the Portfolio may be forced to sell
          its securities at disadvantageous prices. In addition, the Trustees
          may refuse to sell Shares of the Portfolio to any separate account or
          qualified plan or may suspend or terminate the offering of the
          Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of the Portfolio's shareholders.
          It is possible that a qualified plan investing in the Portfolio could
          lose its qualified plan status under the Internal Revenue Code, which
          could have adverse tax consequences on insurance company separate
          accounts investing in the Shares. Janus Capital intends to monitor
          such qualified plans and the Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if a plan loses (or in the
          opinion of Janus Capital is at risk of losing) its qualified plan
          status.

                                                           Other information  13
<PAGE>

          DISTRIBUTION OF THE PORTFOLIO

          The Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

 14 Janus Aspen Series
<PAGE>
                                                         Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolio, the Internal Revenue Code requires
          the Portfolio to distribute net income and any net gains realized on
          its investments annually. The Portfolio's income from dividends and
          interest and any net realized short-term gains are paid to
          shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of the Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of the Portfolio will automatically be
          reinvested into additional Shares of the Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of the Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of the Portfolio's Shares. The Share price of the Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Growth and Income Portfolio declared a dividend in the amount of $0.25
          per share. If the price of Growth and Income Portfolio's Shares was
          $10.00 on December 30, the share price on December 31 would be $9.75,
          barring market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolio may be purchased only through variable
          insurance contracts and qualified plans, it is anticipated that any
          income dividends or capital gains distributions made by the Shares of
          the Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIO

          Dividends, interest and some gains received by the Portfolio on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolio may from year to year make the election permitted
          under Section 853 of the Internal Revenue Code to pass through such
          taxes to shareholders as a foreign tax credit. If such election is not
          made, any foreign taxes paid or accrued will represent an expense to
          the Portfolio which will reduce its investment income.

          The Portfolio does not expect to pay any federal income or excise
          taxes because it intends to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of the Portfolio
          are sold in connection with variable insurance contracts, the
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  15
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIO DIRECTLY.
          SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE INSURANCE
          CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING INSURANCE
          COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. REFER TO THE
          PROSPECTUS FOR THE PARTICIPATING INSURANCE COMPANY'S SEPARATE ACCOUNT
          OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON PURCHASING OR SELLING OF
          VARIABLE INSURANCE CONTRACTS AND ON HOW TO SELECT THE PORTFOLIO AS AN
          INVESTMENT OPTION FOR A CONTRACT OR A QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by the Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolio are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent the Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolio does not price its shares, the NAV of the Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of the Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolio's behalf.

          The Portfolio does not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. The Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of the Portfolio. Although there is no present
          intention to do so, the Portfolio may discontinue sales of its shares
          if management and the Trustees believe that continued sales may
          adversely affect the Portfolio's ability to achieve its investment
          objective. If sales of the Portfolio's Shares are discontinued, it is
          expected that existing participants invested in the Portfolio would be
          permitted to continue to authorize investment in the Portfolio and to
          reinvest any dividends or capital gains distributions, absent highly
          unusual circumstances. The Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of the Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption

 16 Janus Aspen Series
<PAGE>

          proceeds will normally be wired the business day following receipt of
          the redemption order, but in no event later than seven days after
          receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage the Portfolio's investments. The
          Portfolio does not permit frequent trading or market timing. When
          market timing occurs, the Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm the Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash the Portfolio will have to invest. When
          in Janus Capital's opinion such activity would have a disruptive
          effect on portfolio management, the Portfolio reserves the right to
          refuse purchase orders and exchanges into the Portfolio by any person,
          group or commonly controlled account. The Portfolio may notify a
          market timer of rejection of a purchase or exchange order after the
          day the order is placed. If the Portfolio allows a market timer to
          trade Portfolio shares, it may require the market timer to enter into
          a written agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolio that they have
          authorized for investment. Each report will show the investments owned
          by the Portfolio and the market values thereof, as well as other
          information about the Portfolio and its operations. The Trust's fiscal
          year ends December 31.

                                                         Shareholder's guide  17
<PAGE>
Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

 18 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolio may
          invest. The Portfolio may invest in these instruments to the extent
          permitted by its investment objective and policies. The Portfolio is
          not limited by this discussion and may invest in any other types of
          instruments not precluded by the policies discussed elsewhere in this
          Prospectus. Please refer to the SAI for a more detailed discussion of
          certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolio may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, the portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  19
<PAGE>

          Portfolio must pay if these investments are profitable, the Portfolio
          may make various elections permitted by the tax laws. These elections
          could require that the Portfolio recognize taxable income, which in
          turn must be distributed, before the securities are sold and before
          cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by the
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, the Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by the
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by the Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 20 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolio
          does not earn interest on such securities until settlement and bear
          the risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolio may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. It may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolio may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolio may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          The Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  21
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolio may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 22 Janus Aspen Series
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolio.

The Statement of Additional Information provides detailed
information about the Portfolio and is incorporated into this
Prospectus by reference. You may review and copy information about
the Portfolio (including the Portfolio's Statement of Additional
Information) at the Public Reference Room of the SEC or get text
only copies, after paying a duplicating fee, by sending an
electronic request by e-mail to [email protected] or by writing to
or calling the Public Reference Room, Washington, D.C. 20549-0102
(1-202-942-8090). You may also obtain reports and other information
about the Portfolio from the Electronic Data Gathering Analysis and
Retrieval (EDGAR) Database on the SEC's Web site at
http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>
                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              International Growth Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                International Growth Portfolio (the "Portfolio") is a mutual
                fund in Janus Aspen Series and is described in this prospectus.
                The Portfolio currently offers three classes of shares. The
                Service Shares, (the "Shares"), are offered by this prospectus
                in connection with investment in and payments under variable
                annuity contracts and variable life insurance contracts
                (collectively, "variable insurance contracts"), as well as
                certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. See the accompanying
                contract prospectus for information regarding contract fees and
                expenses and any restrictions on purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolio.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   International Growth Portfolio...........................    2
                   Fees and expenses........................................    4
                INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   International Growth Portfolio...........................    5
                   General portfolio policies...............................    7
                   Risks for International Growth Portfolio.................    9
                MANAGEMENT OF THE PORTFOLIO
                   Investment adviser.......................................   11
                   Management expenses and expense limits...................   11
                   Investment personnel.....................................   12
                OTHER INFORMATION...........................................   13
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   15
                   Taxes....................................................   15
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   16
                   Purchases................................................   16
                   Redemptions..............................................   16
                   Frequent trading.........................................   17
                   Shareholder communications...............................   17
                FINANCIAL HIGHLIGHTS........................................   18
                GLOSSARY
                   Glossary of investment terms.............................   19

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

INTERNATIONAL GROWTH PORTFOLIO

          International Growth Portfolio is designed for long-term investors who
          seek growth of capital and who can tolerate the greater risks
          associated with common stock investments.

1. WHAT IS THE INVESTMENT OBJECTIVE OF INTERNATIONAL GROWTH PORTFOLIO?

- --------------------------------------------------------------------------------

          - INTERNATIONAL GROWTH PORTFOLIO seeks long-term growth of capital.

          The Portfolio's Trustees may change this objective without a
          shareholder vote and the Portfolio will notify you of any changes
          that are material. If there is a material change to the Portfolio's
          objective or policies, you should consider whether the Portfolio
          remains an appropriate investment for you. There is no guarantee
          that the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF INTERNATIONAL GROWTH PORTFOLIO?

          The portfolio managers apply a "bottom up" approach in choosing
          investments. In other words, they look for companies with earnings
          growth potential one at a time. If the portfolio managers are unable
          to find investments with earnings growth potential, a significant
          portion of the Portfolio's assets may be in cash or similar
          investments.

          International Growth Portfolio normally invests at least 65% of its
          total assets in securities of issuers from at least five different
          countries, excluding the United States. Although the Portfolio intends
          to invest substantially all of its assets in issuers located outside
          the United States, it may invest in U.S. issuers and it may at times
          invest all of its assets in fewer than five countries, or even a
          single country.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN INTERNATIONAL GROWTH PORTFOLIO?

          The biggest risk of investing in this Portfolio is that its returns
          may vary, and you could lose money. If you are considering investing
          in International Growth Portfolio, remember that it is designed for
          long-term investors who can accept the risks of investing in a
          portfolio with significant common stock holdings. Common stocks tend
          to be more volatile than other investment choices.

          The value of the Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of the
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of the Portfolio's holdings decreases, the
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in the Portfolio you would get back less money.

          The Portfolio may have significant exposure to foreign markets. As a
          result, its returns and NAV may be affected to a large degree by
          fluctuations in currency exchange rates or political or economic
          conditions in a particular country.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

 2 Janus Aspen Series
<PAGE>

          The following information provides some indication of the risks of
          investing in International Growth Portfolio by showing how
          International Growth Portfolio's performance has varied over time. The
          Portfolio's Service Shares commenced operations on December 31, 1999.
          The returns shown for the Service Shares of the Portfolio reflect the
          historical performance of a different class of shares (the
          Institutional Shares) prior to December 31, 1999, restated based on
          the Service Shares' estimated fees and expenses (ignoring any fee and
          expense limitations). The bar chart depicts the change in performance
          from year-to-year during the period indicated but does not include
          charges and expenses attributable to any insurance product which would
          lower the performance illustrated. The Portfolio does not impose any
          sales or other charges that would affect total return computations.
          Total return figures include the effect of the Portfolio's expenses.
          The table compares the average annual returns for the Service Shares
          of the Portfolio for the periods indicated to a broad-based securities
          market index.

           INTERNATIONAL GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                                     23.15%   34.71%   18.36%   16.88%    79.52%
                                      1995     1996     1997     1998      1999

           Best Quarter  4th-1999  56.24%  Worst Quarter  3rd-1998 (17.76%)

                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (5/2/94)
                <S>                                                       <C>       <C>        <C>
                International Growth Portfolio                            79.52%    33.17%         28.19%
                Morgan Stanley Capital International EAFE(R) Index*       26.96%    12.83%         11.22%
                                                                      ----------------------------------------
</TABLE>

           * The Morgan Stanley Capital International EAFE(R) Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 20 Developed Market countries in Europe,
             Australasia and the Far East.

          International Growth Portfolio's past performance does not necessarily
          indicate how it will perform in the future.

                                                          Risk return summary  3
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolio. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of the Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolio in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                                   Distribution                   Total Annual
                                                   Management         (12b-1)        Other       Fund Operating
                                                       Fee            Fees(1)       Expenses       Expenses(2)
    <S>                                            <C>             <C>              <C>          <C>
    International Growth Portfolio                   0.65%            0.25%          0.11%            1.01%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of the Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolio with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in the Portfolio for the time
   periods indicated then redeem all of your shares at the end of those
   periods. The example also assumes that your investment has a 5% return
   each year, and that the Portfolio's operating expenses remain the same.
   Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    International Growth Portfolio                                 $103       $322
</TABLE>

 4 Janus Aspen Series
<PAGE>
                                      Investment objective, principal investment
                                                 strategies and risks

          International Growth Portfolio has a similar investment objective and
          similar principal investment strategies to Janus Overseas Fund.
          Although it is anticipated that the Portfolio and Janus Overseas Fund
          will hold similar securities, differences in asset size, cash flow
          needs and other factors may result in differences in investment
          performance. The expenses of the Portfolio and Janus Overseas Fund are
          expected to differ. The variable contract owner will also bear various
          insurance related costs at the insurance company level. You should
          review the accompanying separate account prospectus for a summary of
          fees and expenses.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          This section takes a closer look at the investment objective of
          International Growth Portfolio, its principal investment strategies
          and certain risks of investing in International Growth Portfolio.
          Strategies and policies that are noted as "fundamental" cannot be
          changed without a shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 9-10 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

          International Growth Portfolio seeks long-term growth of capital.
          Normally, the Portfolio pursues its objective by investing at least
          65% of its total assets in securities of issuers from at least five
          different countries, excluding the United States. Although the
          Portfolio intends to invest substantially all of its assets in issuers
          located outside the United States, it may at times invest in U.S.
          issuers and it may at times invest all of its assets in fewer than
          five countries or even a single country.

The following questions and answers are designed to help you better understand
International Growth Portfolio's principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          The Portfolio may invest substantially all of its assets in common
          stocks if the portfolio managers believe that common stocks will
          appreciate in value. The portfolio managers generally take a "bottom
          up" approach to selecting companies. In other words, they seek to
          identify individual companies with earnings growth potential that may
          not be recognized by the market at large. They make this assessment by
          looking at companies one at a time, regardless of size, country of
          organization, place of principal business activity, or other similar
          selection criteria. Realization of income is not a significant
          consideration when choosing investments for the Portfolio. Income
          realized on the Portfolio's investments may be incidental to its
          objective.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio managers seek companies that meet their
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolio may invest and the
          Portfolio may at times have significant foreign exposure.

              Investment objective, principal investment strategies and risks  5
<PAGE>

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. Although International Growth does not
          emphasize companies of any particular size, a Portfolio with a larger
          asset base is more likely to invest in larger, more established
          issuers.

 6 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          In investing its portfolio assets, the Portfolio will follow the
          general policies listed below. The percentage limitations included in
          these policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if the Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When the portfolio managers believe that market conditions are
          unfavorable for profitable investing, or when they are otherwise
          unable to locate attractive investment opportunities, the Portfolio's
          cash or similar investments may increase. In other words, the
          Portfolio does not always stay fully invested in stocks and bonds.
          Cash or similar investments generally are a residual - they represent
          the assets that remain after a portfolio manager has committed
          available assets to desirable investment opportunities. However, the
          portfolio managers may also temporarily increase the Portfolio's cash
          position to protect its assets or maintain liquidity.

          When the Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          International Growth Portfolio invests primarily in domestic and
          foreign equity securities, which may include preferred stocks, common
          stocks, warrants and securities convertible into common or preferred
          stocks. The Portfolio may also invest to a lesser degree in other
          types of securities. These securities (which are described in the
          Glossary) may include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of the Portfolio's assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          The Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolio's Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolio may invest without limit in foreign equity and debt
          securities. The Portfolio may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

              Investment objective, principal investment strategies and risks  7
<PAGE>

          SPECIAL SITUATIONS
          The Portfolio may invest in special situations. A special situation
          arises when, in the opinion of the Portfolio's managers, the
          securities of a particular issuer will be recognized and appreciate in
          value due to a specific development with respect to that issuer.
          Developments creating a special situation might include, among others,
          a new product or process, a technological breakthrough, a management
          change or other extraordinary corporate event, or differences in
          market supply of and demand for the security. The Portfolio's
          performance could suffer if the anticipated development in a "special
          situation" investment does not occur or does not attract the expected
          attention.

          PORTFOLIO TURNOVER
          The Portfolio generally intends to purchase securities for long-term
          investment although, to a limited extent, the Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. The Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in the Portfolio's holdings whenever the
          portfolio managers believe such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in the Portfolio's
          performance.

 8 Janus Aspen Series
<PAGE>

RISKS FOR INTERNATIONAL GROWTH PORTFOLIO

          Because the Portfolio may invest substantially all of its assets in
          common stocks, the main risk is the risk that the value of the stocks
          it holds might decrease in response to the activities of an individual
          company or in response to general market and/or economic conditions.
          If this occurs, the Portfolio's share price may also decrease. The
          Portfolio's performance may also be affected by risks specific to
          certain types of investments, such as foreign securities, derivative
          investments, non-investment grade debt securities, initial public
          offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in the International Growth Portfolio.

1. THE PORTFOLIO MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW COULD THE PORTFOLIO'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
   PERFORMANCE?

          The Portfolio may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolio's performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as the Portfolio holds a foreign security,
            its value will be affected by the value of the local currency
            relative to the U.S. dollar. When the Portfolio sells a foreign
            denominated security, its value may be worth less in U.S. dollars
            even if the security increases in value in its home country. U.S.
            dollar denominated securities of foreign issuers may also be
            affected by currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may take over the assets or operations of a company or
            that the government may impose taxes or limits on the removal of the
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

              Investment objective, principal investment strategies and risks  9
<PAGE>

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

3. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

4. HOW DOES THE PORTFOLIO TRY TO REDUCE RISK?

          The Portfolio may use futures, options, swaps and other derivative
          instruments to "hedge" or protect its portfolio from adverse movements
          in securities prices and interest rates. The Portfolio may also use a
          variety of currency hedging techniques, including forward currency
          contracts, to manage exchange rate risk. The portfolio managers
          believe the use of these instruments will benefit the Portfolio.
          However, the Portfolio's performance could be worse than if the
          Portfolio had not used such instruments if the portfolio managers'
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 10 Janus Aspen Series
<PAGE>
                                                     Management of the portfolio

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to the Portfolio and is responsible for the
          day-to-day management of the investment portfolio and other business
          affairs of the Portfolio.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning the Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolio, and may be reimbursed by the Portfolio for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolio and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolio's Shares
          may perform certain administrative services relating to the Portfolio
          and Janus Capital or the Portfolio may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          The Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with the Portfolio
          spells out the management fee and other expenses that the Portfolio
          must pay. In addition, the Shares of the Portfolio incur expenses not
          assumed by Janus Capital, including the distribution fee, transfer
          agent and custodian fees and expenses, legal and auditing fees,
          printing and mailing costs of sending reports and other information to
          existing shareholders, and independent Trustees' fees and expenses.
          The Portfolio expects to pay Janus Capital a management fee equal to
          0.65% of average daily net assets during the fiscal year ended
          December 31, 2000. For the fiscal year ended December 31, 1999, the
          Portfolio paid Janus Capital a management fee equal to 0.73% of the
          Portfolio's average net assets. This rate is based on a higher fee
          rate that was previously in effect.

                                                 Management of the portfolio  11
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGERS

LAURENCE J. CHANG
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio which he has
            co-managed since May 1998 and December 1999, respectively. He has
            also co-managed Janus Overseas Fund and Janus Worldwide Fund
            since April 1998 and September 1999, respectively. He served as
            assistant portfolio manager for these funds since 1996. Mr. Chang
            joined Janus Capital in 1993 as a research analyst. He received
            an undergraduate degree with honors in Religion with a
            concentration in Philosophy from Dartmouth College and a Masters
            Degree in Political Science from Stanford University. He has
            earned the right to use the Chartered Financial Analyst
            designation.

HELEN YOUNG HAYES
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio, which she has
            managed or co-managed since inception. Ms. Hayes joined Janus
            Capital in 1987 and has managed or co-managed Janus Worldwide
            Fund and Janus Overseas Fund since their inceptions. She holds a
            Bachelor of Arts in Economics from Yale University and she has
            earned the right to use the Chartered Financial Analyst
            designation.

 12 Janus Aspen Series
<PAGE>
                                                               Other information

          CLASSES OF SHARES

          The Portfolio currently offers three classes of shares, one of which,
          the Service Shares, are offered pursuant to this prospectus. The
          Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of the
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of the Portfolio are
          offered only to qualified plans using plan service providers that are
          compensated for providing distribution and/or record keeping and other
          administrative services provided to plan participants. Because the
          expenses of each class may differ, the performance of each class is
          expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, the Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of the Portfolio. Under the
          terms of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolio does not currently anticipate any disadvantages to
          owners of variable insurance contracts because the Portfolio offers
          its shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in the Portfolio or substitute Shares of
          another Portfolio. If this occurs, the Portfolio may be forced to sell
          its securities at disadvantageous prices. In addition, the Trustees
          may refuse to sell Shares of the Portfolio to any separate account or
          qualified plan or may suspend or terminate the offering of the
          Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of the Portfolio's shareholders.
          It is possible that a qualified plan investing in the Portfolio could
          lose its qualified plan status under the Internal Revenue Code, which
          could have adverse tax consequences on insurance company separate
          accounts investing in the Shares. Janus Capital intends to monitor
          such qualified plans and the Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if a plan loses (or in the
          opinion of Janus Capital is at risk of losing) its qualified plan
          status.

                                                           Other information  13
<PAGE>

          DISTRIBUTION OF THE PORTFOLIO

          The Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

 14 Janus Aspen Series
<PAGE>
                                                         Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolios, the Internal Revenue Code
          requires the Portfolio to distribute net income and any net gains
          realized on its investments annually. The Portfolio's income from
          dividends and interest and any net realized short-term gains are paid
          to shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of the Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of the Portfolio will automatically be
          reinvested into additional Shares of the Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of the Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of the Portfolio's Shares. The Share price of the Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          International Growth Portfolio declared a dividend in the amount of
          $0.25 per share. If the price of International Growth Portfolio's
          Shares was $10.00 on December 30, the share price on December 31 would
          be $9.75, barring market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolio may be purchased only through variable
          insurance contracts and qualified plans, it is anticipated that any
          income dividends or capital gains distributions made by the Shares of
          the Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIO

          Dividends, interest and some gains received by the Portfolio on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolio may from year to year make the election permitted
          under Section 853 of the Internal Revenue Code to pass through such
          taxes to shareholders as a foreign tax credit. If such election is not
          made, any foreign taxes paid or accrued will represent an expense to
          the Portfolio which will reduce its investment income.

          The Portfolio does not expect to pay any federal income or excise
          taxes because it intends to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of the Portfolio
          are sold in connection with variable insurance contracts, the
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  15
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIO DIRECTLY.
          SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE INSURANCE
          CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING INSURANCE
          COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. REFER TO THE
          PROSPECTUS FOR THE PARTICIPATING INSURANCE COMPANY'S SEPARATE ACCOUNT
          OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON PURCHASING OR SELLING OF
          VARIABLE INSURANCE CONTRACTS AND ON HOW TO SELECT THE PORTFOLIO AS AN
          INVESTMENT OPTION FOR A CONTRACT OR A QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by the Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolio are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent the Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolio does not price its shares, the NAV of the Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of the Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolio's behalf.

          The Portfolio does not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. The Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of the Portfolio. Although there is no present
          intention to do so, the Portfolio may discontinue sales of its shares
          if management and the Trustees believe that continued sales may
          adversely affect the Portfolio's ability to achieve its investment
          objective. If sales of the Portfolio's Shares are discontinued, it is
          expected that existing participants invested in the Portfolio would be
          permitted to continue to authorize investment in the Portfolio and to
          reinvest any dividends or capital gains distributions, absent highly
          unusual circumstances. The Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of the Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption

 16 Janus Aspen Series
<PAGE>

          proceeds will normally be wired the business day following receipt of
          the redemption order, but in no event later than seven days after
          receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage the Portfolio's investments. The
          Portfolio does not permit frequent trading or market timing. When
          market timing occurs, the Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm the Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash the Portfolio will have to invest. When
          in Janus Capital's opinion such activity would have a disruptive
          effect on portfolio management, the Portfolio reserves the right to
          refuse purchase orders and exchanges into the Portfolio by any person,
          group or commonly controlled account. The Portfolio may notify a
          market timer of rejection of a purchase or exchange order after the
          day the order is placed. If the Portfolio allows a market timer to
          trade Portfolio shares, it may require the market timer to enter into
          a written agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolio that they have
          authorized for investment. Each report will show the investments owned
          by the Portfolio and the market values thereof, as well as other
          information about the Portfolio and its operations. The Trust's fiscal
          year ends December 31.

                                                         Shareholder's guide  17
<PAGE>
Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

 18 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolios may
          invest. The Portfolio may invest in these instruments to the extent
          permitted by its investment objective and policies. The Portfolio is
          not limited by this discussion and may invest in any other types of
          instruments not precluded by the policies discussed elsewhere in this
          Prospectus. Please refer to the SAI for a more detailed discussion of
          certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolio may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, the portfolio managers may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  19
<PAGE>

          Portfolio must pay if these investments are profitable, the Portfolio
          may make various elections permitted by the tax laws. These elections
          could require that the Portfolio recognize taxable income, which in
          turn must be distributed, before the securities are sold and before
          cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by the
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, the Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by the
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by the Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 20 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolio
          does not earn interest on such securities until settlement and bear
          the risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolio may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. It may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolio may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolio may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          The Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  21
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolio may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 22 Janus Aspen Series
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolio.

The Statement of Additional Information provides detailed
information about the Portfolio and is incorporated into this
Prospectus by reference. You may review the Portfolio's Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>


                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Worldwide Growth Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                Worldwide Growth Portfolio (the "Portfolio") is a mutual fund in
                Janus Aspen Series and is described in this prospectus. The
                Portfolio currently offers three classes of shares. The Service
                Shares, (the "Shares"), are offered by this prospectus in
                connection with investment in and payments under variable
                annuity contracts and variable life insurance contracts
                (collectively, "variable insurance contracts"), as well as
                certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. See the accompanying
                contract prospectus for information regarding contract fees and
                expenses and any restrictions on purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolio.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Worldwide Growth Portfolio...............................    2
                   Fees and expenses........................................    4
                INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Worldwide Growth Portfolio...............................    5
                   General portfolio policies...............................    7
                   Risks for Worldwide Growth Portfolio.....................    9
                MANAGEMENT OF THE PORTFOLIO
                   Investment adviser.......................................   11
                   Management expenses and expense limits...................   11
                   Investment personnel.....................................   12
                OTHER INFORMATION...........................................   13
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   15
                   Taxes....................................................   15
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   16
                   Purchases................................................   16
                   Redemptions..............................................   16
                   Frequent trading.........................................   17
                   Shareholder communications...............................   17
                FINANCIAL HIGHLIGHTS........................................   18
                GLOSSARY
                   Glossary of investment terms.............................   19

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

WORLDWIDE GROWTH PORTFOLIO

          Worldwide Growth Portfolio is designed for long-term investors who
          seek growth of capital and who can tolerate the greater risks
          associated with common stock investments.

1. WHAT IS THE INVESTMENT OBJECTIVE OF WORLDWIDE GROWTH PORTFOLIO?

- --------------------------------------------------------------------------------

          - WORLDWIDE GROWTH PORTFOLIO seeks long-term growth of capital in a
            manner consistent with the preservation of capital.

          The Portfolio's Trustees may change this objective without a
          shareholder vote and the Portfolio will notify you of any changes that
          are material. If there is a material change to the Portfolio's
          objective or policies, you should consider whether the Portfolio
          remains an appropriate investment for you. There is no guarantee that
          the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF WORLDWIDE GROWTH PORTFOLIO?

          The portfolio managers apply a "bottom up" approach in choosing
          investments. In other words, they look for companies with earnings
          growth potential one at a time. If the portfolio managers are unable
          to find investments with earnings growth potential, a significant
          portion of the Portfolio's assets may be in cash or similar
          investments.

          Worldwide Growth Portfolio invests primarily in common stocks of
          companies of any size throughout the world. The Portfolio normally
          invests in issuers from at least five different countries, including
          the United States. The Portfolio may at times invest in fewer than
          five countries or even a single country.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN WORLDWIDE GROWTH PORTFOLIO?

          The biggest risk of investing in this Portfolio is that its returns
          may vary, and you could lose money. If you are considering investing
          in Worldwide Growth Portfolio, remember that it is designed for
          long-term investors who can accept the risks of investing in a
          portfolio with significant common stock holdings. Common stocks tend
          to be more volatile than other investment choices.

          The value of the Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of the
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of the Portfolio's holdings decreases, the
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in the Portfolio you would get back less money.

          Worldwide Growth Portfolio may have significant exposure to foreign
          markets. As a result, its returns and NAV may be affected to a large
          degree by fluctuations in currency exchange rates or political or
          economic conditions in a particular country.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in Worldwide Growth Portfolio by showing how Worldwide
          Growth Portfolio's performance has varied over time. The Portfolio's
          Service Shares commenced operations on December 31, 1999. The returns
          shown for the Service Shares of the Portfolio reflect the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses (ignoring any fee and expense
          limitations). The bar chart depicts the change in performance from
          year-to-year during the period indicated but does not include charges
          and expenses attributable to any insurance product which

 2 Janus Aspen Series
<PAGE>

          would lower the performance illustrated. The Portfolio does not impose
          any sales or other charges that would affect total return
          computations. Total return figures include the effect of the
          Portfolio's expenses. The table compares the average annual returns
          for the Service Shares of the Portfolio for the periods indicated to a
          broad-based securities market index.

           WORLDWIDE GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                             1.53%   27.29%   28.80%   21.91%   28.71%    63.49%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1999  41.62%  Worst Quarter  3rd-1998 (17.00%)

                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Worldwide Growth Portfolio                                63.49%    33.28%         29.35%
                Morgan Stanley Capital International World Index*         24.93%    19.76%         16.41%
                                                                      --------------------------------------------
</TABLE>

           * The Morgan Stanley Capital International World Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 21 Developed Market countries in North
             America, Europe and the Asia/Pacific Region.

          Worldwide Growth Portfolio's past performance does not necessarily
          indicate how it will perform in the future.

                                                          Risk return summary  3
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolio. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of the Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolio in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                        Distribution                 Total Annual Fund
                                         Management        (12b-1)        Other          Operating
                                             Fee           Fees(1)      Expenses        Expenses(2)
    <S>                                  <C>            <C>             <C>          <C>
    Worldwide Growth Portfolio              0.65%           0.25%         0.05%           0.95%
 </TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of the Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolio with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in the Portfolio for the time
   periods indicated then redeem all of your shares at the end of those
   periods. The example also assumes that your investment has a 5% return
   each year, and that the Portfolio's operating expenses remain the same.
   Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Worldwide Growth Portfolio                                     $ 97      $  303
</TABLE>

 4 Janus Aspen Series
<PAGE>
                                      Investment objective, principal investment
                                                 strategies and risks

          Worldwide Growth Portfolio has a similar investment objective and
          similar principal investment strategies to Janus Worldwide Fund.
          Although it is anticipated that the Portfolio and Janus Worldwide Fund
          will hold similar securities, differences in asset size, cash flow
          needs and other factors may result in differences in investment
          performance. The expenses of the Portfolio and Janus Worldwide Fund
          are expected to differ. The variable contract owner will also bear
          various insurance related costs at the insurance company level. You
          should review the accompanying separate account prospectus for a
          summary of fees and expenses.

INVESTMENT OBJECTIVES AND PRINCIPAL INVESTMENT STRATEGIES

          This section takes a closer look at the investment objective of
          Worldwide Growth Portfolio, its principal investment strategies and
          certain risks of investing in Worldwide Growth Portfolio. Strategies
          and policies that are noted as "fundamental" cannot be changed without
          a shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 9-10 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

          Worldwide Growth Portfolio seeks long-term growth of capital in a
          manner consistent with the preservation of capital. It pursues its
          objective by investing primarily in common stocks of companies of any
          size throughout the world. The Portfolio normally invests in issuers
          from at least five different countries, including the United States.
          The Portfolio may at times invest in fewer than five countries or even
          a single country.

The following questions and answers are designed to help you better understand
Worldwide Growth Portfolio's principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          The Portfolio may invest substantially all of its assets in common
          stocks if the portfolio managers believe that common stocks will
          appreciate in value. The portfolio managers generally take a "bottom
          up" approach to selecting companies. In other words, they seek to
          identify individual companies with earnings growth potential that may
          not be recognized by the market at large. They make this assessment by
          looking at companies one at a time, regardless of size, country of
          organization, place of principal business activity, or other similar
          selection criteria. Realization of income is not a significant
          consideration when choosing investments for the Portfolio. Income
          realized on the Portfolio's investments may be incidental to its
          objective.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio managers seek companies that meet their
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolio may invest and the
          Portfolio may at times have significant foreign exposure.

              Investment objective, principal investment strategies and risks  5
<PAGE>

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. Although Worldwide Growth Portfolio does not
          emphasize companies of any particular size, a Portfolio with a larger
          asset base is more likely to invest in larger, more established
          issuers.

 6 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          In investing its portfolio assets, the Portfolio will follow the
          general policies listed below. The percentage limitations included in
          these policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if the Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When the portfolio managers believe that market conditions are
          unfavorable for profitable investing, or when they are otherwise
          unable to locate attractive investment opportunities, the Portfolio's
          cash or similar investments may increase. In other words, the
          Portfolio does not always stay fully invested in stocks and bonds.
          Cash or similar investments generally are a residual - they represent
          the assets that remain after a portfolio manager has committed
          available assets to desirable investment opportunities. However, the
          portfolio managers may also temporarily increase the Portfolio's cash
          position to protect its assets or maintain liquidity.

          When the Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          Worldwide Growth Portfolio invests primarily in domestic and foreign
          equity securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Portfolio may also invest to a lesser degree in other types of
          securities. These securities (which are described in the Glossary) may
          include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of the Portfolio's assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          The Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolio's Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolio may invest without limit in foreign equity and debt
          securities. The Portfolio may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United

              Investment objective, principal investment strategies and risks  7
<PAGE>

          States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

          SPECIAL SITUATIONS
          The Portfolio may invest in special situations. A special situation
          arises when, in the opinion of the Portfolio's managers, the
          securities of a particular issuer will be recognized and appreciate in
          value due to a specific development with respect to that issuer.
          Developments creating a special situation might include, among others,
          a new product or process, a technological breakthrough, a management
          change or other extraordinary corporate event, or differences in
          market supply of and demand for the security. The Portfolio's
          performance could suffer if the anticipated development in a "special
          situation" investment does not occur or does not attract the expected
          attention.

          PORTFOLIO TURNOVER
          The Portfolio generally intends to purchase securities for long-term
          investment although, to a limited extent, the Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. The Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in the Portfolio's holdings whenever the
          portfolio managers believe such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in the Portfolio's
          performance.

 8 Janus Aspen Series
<PAGE>

RISKS FOR WORLDWIDE GROWTH PORTFOLIO

          Because the Portfolio may invest substantially all of its assets in
          common stocks, the main risk is the risk that the value of the stocks
          it holds might decrease in response to the activities of an individual
          company or in response to general market and/or economic conditions.
          If this occurs, the Portfolio's share price may also decrease. The
          Portfolio's performance may also be affected by risks specific to
          certain types of investments, such as foreign securities, derivative
          investments, non-investment grade debt securities, initial public
          offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in Worldwide Growth Portfolio.

1. THE PORTFOLIO MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW COULD THE PORTFOLIO'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
   PERFORMANCE?

          The Portfolio may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolio's performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as the Portfolio holds a foreign security,
            its value will be affected by the value of the local currency
            relative to the U.S. dollar. When the Portfolio sells a foreign
            denominated security, its value may be worth less in U.S. dollars
            even if the security increases in value in its home country. U.S.
            dollar denominated securities of foreign issuers may also be
            affected by currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may take over the assets or operations of a company or
            that the government may impose taxes or limits on the removal of the
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

              Investment objective, principal investment strategies and risks  9
<PAGE>

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

3. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

4. HOW DOES THE PORTFOLIO TRY TO REDUCE RISK?

          The Portfolio may use futures, options, swaps and other derivative
          instruments to "hedge" or protect its portfolio from adverse movements
          in securities prices and interest rates. The Portfolio may also use a
          variety of currency hedging techniques, including forward currency
          contracts, to manage exchange rate risk. The portfolio managers
          believe the use of these instruments will benefit the Portfolio.
          However, the Portfolio's performance could be worse than if the
          Portfolio had not used such instruments if the portfolio managers'
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 10 Janus Aspen Series
<PAGE>
                                                     Management of the portfolio

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to the Portfolio and is responsible for the
          day-to-day management of the investment portfolio and other business
          affairs of the Portfolio.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning the Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolio, and may be reimbursed by the Portfolio for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolio and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolio's Shares
          may perform certain administrative services relating to the Portfolio
          and Janus Capital or the Portfolio may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          The Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with the Portfolio
          spells out the management fee and other expenses that the Portfolio
          must pay. In addition, the Shares of the Portfolio incur expenses not
          assumed by Janus Capital, including the distribution fee, transfer
          agent and custodian fees and expenses, legal and auditing fees,
          printing and mailing costs of sending reports and other information to
          existing shareholders, and independent Trustees' fees and expenses.
          The Portfolio expects to pay Janus Capital a management fee equal to
          0.65% of average daily net assets during the fiscal year ended
          December 31, 2000. For the fiscal year ended December 31, 1999, the
          Portfolio paid Janus Capital a management fee equal to 0.66% of the
          Portfolio's average net assets. This rate is based on a higher fee
          rate that was previously in effect.

                                                 Management of the portfolio  11
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGERS

LAURENCE J. CHANG
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio which he has
            co-managed since May 1998 and December 1999, respectively. He has
            also co-managed Janus Overseas Fund and Janus Worldwide Fund
            since April 1998 and September 1999, respectively. He served as
            assistant portfolio manager for these funds since 1996. Mr. Chang
            joined Janus Capital in 1993 as a research analyst. He received
            an undergraduate degree with honors in Religion with a
            concentration in Philosophy from Dartmouth College and a Masters
            Degree in Political Science from Stanford University. He has
            earned the right to use the Chartered Financial Analyst
            designation.

HELEN YOUNG HAYES
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio, which she has
            managed or co-managed since inception. Ms. Hayes joined Janus
            Capital in 1987 and has managed or co-managed Janus Worldwide
            Fund and Janus Overseas Fund since their inceptions. She holds a
            Bachelor of Arts in Economics from Yale University and she has
            earned the right to use the Chartered Financial Analyst
            designation.

 12 Janus Aspen Series
<PAGE>
                                                               Other information

          CLASSES OF SHARES

          The Portfolio currently offers three classes of shares, one of which,
          the Service Shares, are offered pursuant to this prospectus. The
          Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of the
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of the Portfolio are
          offered only to qualified plans using plan service providers that are
          compensated for providing distribution and/or record keeping and other
          administrative services provided to plan participants. Because the
          expenses of each class may differ, the performance of each class is
          expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, the Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of the Portfolio. Under the
          terms of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolio does not currently anticipate any disadvantages to
          owners of variable insurance contracts because the Portfolio offers
          its shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in the Portfolio or substitute Shares of
          another Portfolio. If this occurs, the Portfolio may be forced to sell
          its securities at disadvantageous prices. In addition, the Trustees
          may refuse to sell Shares of the Portfolio to any separate account or
          qualified plan or may suspend or terminate the offering of the
          Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of the Portfolio's shareholders.
          It is possible that a qualified plan investing in the Portfolio could
          lose its qualified plan status under the Internal Revenue Code, which
          could have adverse tax consequences on insurance company separate
          accounts investing in the Shares. Janus Capital intends to monitor
          such qualified plans and the Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if a plan loses (or in the
          opinion of Janus Capital is at risk of losing) its qualified plan
          status.

                                                           Other information  13
<PAGE>

          DISTRIBUTION OF THE PORTFOLIO

          The Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

 14 Janus Aspen Series
<PAGE>
                                                         Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolio, the Internal Revenue Code requires
          the Portfolio to distribute net income and any net gains realized on
          its investments annually. The Portfolio's income from dividends and
          interest and any net realized short-term gains are paid to
          shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of the Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of the Portfolio will automatically be
          reinvested into additional Shares of the Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of the Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of the Portfolio's Shares. The Share price of the Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Worldwide Growth Portfolio declared a dividend in the amount of $0.25
          per share. If the price of Worldwide Growth Portfolio's Shares was
          $10.00 on December 30, the share price on December 31 would be $9.75,
          barring market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolio may be purchased only through variable
          insurance contracts and qualified plans, it is anticipated that any
          income dividends or capital gains distributions made by the Shares of
          the Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIO

          Dividends, interest and some gains received by the Portfolio on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolio may from year to year make the election permitted
          under Section 853 of the Internal Revenue Code to pass through such
          taxes to shareholders as a foreign tax credit. If such election is not
          made, any foreign taxes paid or accrued will represent an expense to
          the Portfolio which will reduce its investment income.

          The Portfolio does not expect to pay any federal income or excise
          taxes because it intends to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of the Portfolio
          are sold in connection with variable insurance contracts, the
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  15
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIO DIRECTLY.
          SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE INSURANCE
          CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING INSURANCE
          COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. REFER TO THE
          PROSPECTUS FOR THE PARTICIPATING INSURANCE COMPANY'S SEPARATE ACCOUNT
          OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON PURCHASING OR SELLING OF
          VARIABLE INSURANCE CONTRACTS AND ON HOW TO SELECT THE PORTFOLIO AS AN
          INVESTMENT OPTION FOR A CONTRACT OR A QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by the Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolio are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent the Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolio does not price its shares, the NAV of the Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of the Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolio's behalf.

          The Portfolio does not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. The Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of the Portfolio. Although there is no present
          intention to do so, the Portfolio may discontinue sales of its shares
          if management and the Trustees believe that continued sales may
          adversely affect the Portfolio's ability to achieve its investment
          objective. If sales of the Portfolio's Shares are discontinued, it is
          expected that existing participants invested in the Portfolio would be
          permitted to continue to authorize investment in the Portfolio and to
          reinvest any dividends or capital gains distributions, absent highly
          unusual circumstances. The Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of the Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption

 16 Janus Aspen Series
<PAGE>

          proceeds will normally be wired the business day following receipt of
          the redemption order, but in no event later than seven days after
          receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage the Portfolio's investments. The
          Portfolio does not permit frequent trading or market timing. When
          market timing occurs, the Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm the Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash the Portfolio will have to invest. When
          in Janus Capital's opinion such activity would have a disruptive
          effect on portfolio management, the Portfolio reserves the right to
          refuse purchase orders and exchanges into the Portfolio by any person,
          group or commonly controlled account. The Portfolio may notify a
          market timer of rejection of a purchase or exchange order after the
          day the order is placed. If the Portfolio allows a market timer to
          trade Portfolio shares, it may require the market timer to enter into
          a written agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolio that they have
          authorized for investment. Each report will show the investments owned
          by the Portfolio and the market values thereof, as well as other
          information about the Portfolio and its operations. The Trust's fiscal
          year ends December 31.

                                                         Shareholder's guide  17
<PAGE>
Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

 18 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolio may
          invest. The Portfolio may invest in these instruments to the extent
          permitted by its investment objective and policies. The Portfolio is
          not limited by this discussion and may invest in any other types of
          instruments not precluded by the policies discussed elsewhere in this
          Prospectus. Please refer to the SAI for a more detailed discussion of
          certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolio may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, the portfolio managers may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  19
<PAGE>

          Portfolio must pay if these investments are profitable, the Portfolio
          may make various elections permitted by the tax laws. These elections
          could require that the Portfolio recognize taxable income, which in
          turn must be distributed, before the securities are sold and before
          cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by the
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, the Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by the
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by the Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 20 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolio
          does not earn interest on such securities until settlement and bear
          the risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolio may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. It may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolio may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolio may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          The Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  21
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolio may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 22 Janus Aspen Series
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolio.

The Statement of Additional Information provides detailed
information about the Portfolio and is incorporated into this
Prospectus by reference. You may review the Portfolio's Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>

                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Global Technology Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                Global Technology Portfolio (the "Portfolio") is a mutual fund
                in Janus Aspen Series and is described in this prospectus. The
                Portfolio currently offers two classes of shares. The Service
                Shares, (the "Shares"), are offered by this prospectus in
                connection with investment in and payments under variable
                annuity contracts and variable life insurance contracts
                (collectively, "variable insurance contracts"), as well as
                certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. See the accompanying
                contract prospectus for information regarding contract fees and
                expenses and any restrictions on purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolio.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Global Technology Portfolio..............................    2
                   Fees and expenses........................................    4
                INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Global Technology Portfolio..............................    5
                   General portfolio policies...............................    7
                   Risks for Global Technology Portfolio....................    9
                MANAGEMENT OF THE PORTFOLIO
                   Investment adviser.......................................   11
                   Management expenses and expense limits...................   11
                   Investment personnel.....................................   12
                OTHER INFORMATION...........................................   13
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   15
                   Taxes....................................................   15
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   16
                   Purchases................................................   16
                   Redemptions..............................................   16
                   Frequent trading.........................................   17
                   Shareholder communications...............................   17
                FINANCIAL HIGHLIGHTS........................................   18
                GLOSSARY
                   Glossary of investment terms.............................   19

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

GLOBAL TECHNOLOGY PORTFOLIO

          Global Technology Portfolio is designed for long-term investors who
          seek growth of capital and who can tolerate the greater risks
          associated with common stock investments.

1. WHAT IS THE INVESTMENT OBJECTIVE OF GLOBAL TECHNOLOGY PORTFOLIO?

- --------------------------------------------------------------------------------

          - GLOBAL TECHNOLOGY PORTFOLIO seeks long-term growth of capital.

          The Portfolio's Trustees may change this objective without a
          shareholder vote and the Portfolio will notify you of any changes that
          are material. If there is a material change to the Portfolio's
          objective or policies, you should consider whether the Portfolio
          remains an appropriate investment for you. There is no guarantee that
          the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF GLOBAL TECHNOLOGY PORTFOLIO?

          The portfolio manager applies a "bottom up" approach in choosing
          investments. In other words, he looks for companies with earnings
          growth potential one at a time. If the portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of the Portfolio's assets may be in cash or similar investments.

          Global Technology Portfolio invests primarily in equity securities of
          U.S. and foreign companies selected for their growth potential. Under
          normal circumstances, it invests at least 65% of its total assets in
          securities of companies that the portfolio manager believes will
          benefit significantly from advances or improvements in technology.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN GLOBAL TECHNOLOGY PORTFOLIO?

          The biggest risk of investing in this Portfolio is that its returns
          may vary, and you could lose money. If you are considering investing
          in Global Technology Portfolio, remember that it is designed for
          long-term investors who can accept the risks of investing in a
          portfolio with significant common stock holdings. Common stocks tend
          to be more volatile than other investment choices.

          The value of the Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of the
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of the Portfolio's holdings decreases, the
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in the Portfolio you would get back less money.

          Although the Portfolio does not concentrate its investments in
          specific industries, it may invest in companies related in such a way
          that they react similarly to certain market pressures. For example,
          competition among technology companies may result in increasingly
          aggressive pricing of their products and services, which may affect
          the profitability of companies in the portfolio. In addition, because
          of the rapid pace of technological development, products or services
          developed by companies in the Portfolio's portfolio may become rapidly
          obsolete or have relatively short product cycles. As a result, the
          Portfolio's returns may be considerably more volatile than the returns
          of a fund that does not invest in similarly related companies.

          The Portfolio may have significant exposure to foreign markets. As a
          result, its returns and NAV may be affected to a large degree by
          fluctuations in currency exchange rates or political or economic
          conditions in a particular country.

 2 Janus Aspen Series
<PAGE>

          The Portfolio is nondiversified. In other words, it may hold larger
          positions in a smaller number of securities than a diversified fund.
          As a result, a single security's increase or decrease in value may
          have a greater impact on the Portfolio's NAV and total return.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          Since Global Technology Portfolio did not commence operations until
          January 15, 2000, there is no performance available as of the date of
          this prospectus.

                                                          Risk return summary  3
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolio. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of the Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolio in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                     Distribution                        Total Annual Fund
                                    Management          (12b-1)            Other             Operating
                                        Fee             Fees(1)          Expenses           Expenses(2)
    <S>                             <C>              <C>                 <C>             <C>
    Global Technology Portfolio        0.65%             0.25%             0.13%               1.03%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of the Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolio with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in the Portfolio for the time
   periods indicated then redeem all of your shares at the end of those
   periods. The example also assumes that your investment has a 5% return
   each year, and that the Portfolio's operating expenses remain the same.
   Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Global Technology Portfolio                                    $105      $  328
</TABLE>

 4 Janus Aspen Series
<PAGE>
                                      Investment objective, principal investment
                                                 strategies and risks

          Global Technology Portfolio has a similar investment objective and
          similar principal investment strategies to Janus Global Technology
          Fund. Although it is anticipated that the Portfolio and Janus Global
          Technology Fund will hold similar securities, differences in asset
          size, cash flow needs and other factors may result in differences in
          investment performance. The expenses of the Portfolio and Janus Global
          Technology Fund are expected to differ. The variable contract owner
          will also bear various insurance related costs at the insurance
          company level. You should review the accompanying separate account
          prospectus for a summary of fees and expenses.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          This section takes a closer look at the investment objective of Global
          Technology Portfolio, its principal investment strategies and certain
          risks of investing in Global Technology Portfolio. Strategies and
          policies that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 9-10 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

          Global Technology Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in equity securities of
          U.S. and foreign companies selected for their growth potential.
          Normally, it invests at least 65% of its total assets in securities of
          companies that the portfolio manager believes will benefit
          significantly from advances or improvements in technology. These
          companies generally fall into two categories:

          a. Companies that the portfolio manager believes have or will develop
          products, processes or services that will provide significant
          technological advancements or improvements; and

          b. Companies that the portfolio manager believes rely extensively on
          technology in connection with their operations or services.

The following questions and answers are designed to help you better understand
Global Technology Portfolio's principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          The Portfolio may invest substantially all of its assets in common
          stocks if the portfolio manager believes that common stocks will
          appreciate in value. The portfolio manager generally takes a "bottom
          up" approach to selecting companies. In other words, he seeks to
          identify individual companies with earnings growth potential that may
          not be recognized by the market at large. He makes this assessment by
          looking at companies one at a time, regardless of size, country of
          organization, place of principal business activity, or other similar
          selection criteria. Realization of income is not a significant
          consideration when choosing investments for the Portfolio. Income
          realized on the Portfolio's investments may be incidental to its
          objective.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio manager seeks companies that meet his
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency

              Investment objective, principal investment strategies and risks  5
<PAGE>

          relationships, and prospects for economic growth among countries,
          regions or geographic areas may warrant greater consideration in
          selecting foreign securities. There are no limitations on the
          countries in which the Portfolio may invest and the Portfolio may at
          times have significant foreign exposure.

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. Although Global Technology Portfolio does not
          emphasize companies of any particular size, a Portfolio with a larger
          asset base is more likely to invest in larger, more established
          issuers.

4. WHAT IS GLOBAL TECHNOLOGY PORTFOLIO'S INDUSTRY POLICY?

          Global Technology Portfolio will not concentrate its investments in
          any particular industry or group of related industries. As a result,
          the portfolio manager may have more flexibility to find companies that
          he believes will benefit from advances or improvements in technology
          in a number of industries. Nevertheless, the Portfolio may hold a
          significant portion of its assets in industries such as:
          aerospace/defense; biotechnology; computers; office/business
          equipment; semi-conductors; software; telecommunications; and
          telecommunications equipment.

 6 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          In investing its portfolio assets, the Portfolio will follow the
          general policies listed below. The percentage limitations included in
          these policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if the Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When the portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he is otherwise unable
          to locate attractive investment opportunities, the Portfolio's cash or
          similar investments may increase. In other words, the Portfolio does
          not always stay fully invested in stocks and bonds. Cash or similar
          investments generally are a residual - they represent the assets that
          remain after the portfolio manager has committed available assets to
          desirable investment opportunities. However, the portfolio manager may
          also temporarily increase the Portfolio's cash position to protect its
          assets or maintain liquidity.

          When the Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          Global Technology Portfolio invests primarily in domestic and foreign
          equity securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Portfolio may also invest to a lesser degree in other types of
          securities. These securities (which are described in the Glossary) may
          include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of the Portfolio's assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          The Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolio's Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolio may invest without limit in foreign equity and debt
          securities. The Portfolio may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

              Investment objective, principal investment strategies and risks  7
<PAGE>

          SPECIAL SITUATIONS
          The Portfolio may invest in special situations. A special situation
          arises when, in the opinion of the Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. The Portfolio's performance
          could suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolio generally intends to purchase securities for long-term
          investment although, to a limited extent, the Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. The Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in the Portfolio's holdings whenever the
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Global Technology Portfolio may invest in companies with relatively
          short product cycles, for example, 6 to 9 months. Consequently its
          portfolio turnover may be more frequent. Increased portfolio turnover
          may result in higher costs for brokerage commissions, dealer mark-ups
          and other transaction costs and may also result in taxable capital
          gains. Higher costs associated with increased portfolio turnover may
          offset gains in the Portfolio's performance.

 8 Janus Aspen Series
<PAGE>

RISKS FOR GLOBAL TECHNOLOGY PORTFOLIO

          Because the Portfolio may invest substantially all of its assets in
          common stocks, the main risk is the risk that the value of the stocks
          it holds might decrease in response to the activities of an individual
          company or in response to general market and/or economic conditions.
          If this occurs, the Portfolio's share price may also decrease. The
          Portfolio's performance may also be affected by risks specific to
          certain types of investments, such as foreign securities, derivative
          investments, non-investment grade debt securities, initial public
          offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.
          Global Technology Portfolio's performance may also be affected by
          industry risk.

The following questions and answers are designed to help you better understand
some of the risks of investing in Global Technology Portfolio.

1. THE PORTFOLIO MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF GLOBAL TECHNOLOGY PORTFOLIO AFFECT ITS
   RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of the Portfolio.

3. HOW COULD THE PORTFOLIO'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
   PERFORMANCE?

          The Portfolio may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolio's performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as the Portfolio holds a foreign security,
            its value will be affected by the value of the local currency
            relative to the U.S. dollar. When the Portfolio sells a foreign
            denominated security, its value may be worth less in U.S. dollars
            even if the security increases in value in its home country. U.S.
            dollar denominated securities of foreign issuers may also be
            affected by currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may

              Investment objective, principal investment strategies and risks  9
<PAGE>

            take over the assets or operations of a company or that the
            government may impose taxes or limits on the removal of the
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

4. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

5. HOW DOES THE PORTFOLIO TRY TO REDUCE RISK?

          The Portfolio may use futures, options, swaps and other derivative
          instruments to "hedge" or protect its portfolio from adverse movements
          in securities prices and interest rates. The Portfolio may also use a
          variety of currency hedging techniques, including forward currency
          contracts, to manage exchange rate risk. The portfolio manager
          believes the use of these instruments will benefit the Portfolio.
          However, the Portfolio's performance could be worse than if the
          Portfolio had not used such instruments if the portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

6. WHAT IS "INDUSTRY RISK"?

          Industry risk is the possibility that a group of related stocks will
          decline in price due to industry-specific developments. Companies in
          the same or similar industries may share common characteristics and
          are more likely to react similarly to industry-specific market or
          economic developments. In technology-related industries, competitive
          pressures may have a significant effect on the performance of
          companies in which Global Technology Portfolio may invest. In
          addition, technology and technology-related companies often progress
          at an accelerated rate, and these companies may be subject to short
          product cycles and aggressive pricing which may increase their
          volatility. Although Global Technology Portfolio does not
          "concentrate" in a specific group of industries, it may, at times,
          have significant exposure to companies in a variety of
          technology-related industries.

 10 Janus Aspen Series
<PAGE>
                                                     Management of the portfolio

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to the Portfolio and is responsible for the
          day-to-day management of the investment portfolio and other business
          affairs of the Portfolio.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning the Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolio, and may be reimbursed by the Portfolio for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolio and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolio's Shares
          may perform certain administrative services relating to the Portfolio
          and Janus Capital or the Portfolio may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          The Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with the Portfolio
          spells out the management fee and other expenses that the Portfolio
          must pay. In addition, the Shares of the Portfolio incur expenses not
          assumed by Janus Capital, including the distribution fee, transfer
          agent and custodian fees and expenses, legal and auditing fees,
          printing and mailing costs of sending reports and other information to
          existing shareholders, and independent Trustees' fees and expenses.
          The Portfolio expects to pay Janus Capital a management fee equal to
          0.65% of average daily net assets during its initial fiscal year.
          Janus Capital has agreed to limit the Portfolio's expenses to 1.25%
          until at least the next annual renewal of the advisory agreements. As
          noted in the fee table on page 4, however, the Portfolio's expenses
          without waivers are not expected to exceed the expense limit.

                                                 Management of the portfolio  11
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGER

C. MIKE LU
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Global
            Technology Portfolio and Janus Global Technology Fund, which he
            has managed since inception. He joined Janus Capital in 1991 as a
            research analyst and has consistently focused on companies in the
            technology industry. Mr. Lu has a Bachelor of Arts in History and
            a Bachelor of Arts in Economics from Yale University. Mr. Lu has
            earned the right to use the Chartered Financial Analyst
            designation.

 12 Janus Aspen Series
<PAGE>
                                                               Other information

          CLASSES OF SHARES

          The Portfolio currently offers two classes of shares, one of which,
          the Service Shares, are offered pursuant to this prospectus. The
          Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of the
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Because the expenses of each class may
          differ, the performance of each class is expected to differ. If you
          would like additional information about the Institutional Shares,
          please call 1-800-525-0020.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of the Portfolio. Under the
          terms of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolio does not currently anticipate any disadvantages to
          owners of variable insurance contracts because the Portfolio offers
          its shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in the Portfolio or substitute Shares of
          another Portfolio. If this occurs, the Portfolio may be forced to sell
          its securities at disadvantageous prices. In addition, the Trustees
          may refuse to sell Shares of the Portfolio to any separate account or
          qualified plan or may suspend or terminate the offering of the
          Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of the Portfolio's shareholders.
          It is possible that a qualified plan investing in the Portfolio could
          lose its qualified plan status under the Internal Revenue Code, which
          could have adverse tax consequences on insurance company separate
          accounts investing in the Shares. Janus Capital intends to monitor
          such qualified plans and the Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if a plan loses (or in the
          opinion of Janus Capital is at risk of losing) its qualified plan
          status.

          DISTRIBUTION OF THE PORTFOLIO

          The Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

                                                           Other information  13
<PAGE>
Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolio, the Internal Revenue Code requires
          the Portfolio to distribute net income and any net gains realized on
          its investments annually. The Portfolio's income from dividends and
          interest and any net realized short-term gains are paid to
          shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of the Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of the Portfolio will automatically be
          reinvested into additional Shares of the Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of the Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of the Portfolio's Shares. The Share price of the Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Global Technology Portfolio declared a dividend in the amount of $0.25
          per share. If the price of Global Technology Portfolio's Shares was
          $10.00 on December 30, the share price on December 31 would be $9.75,
          barring market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolio may be purchased only through variable
          insurance contracts and qualified plans, it is anticipated that any
          income dividends or capital gains distributions made by the Shares of
          the Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIO

          Dividends, interest and some gains received by the Portfolio on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolio may from year to year make the election permitted
          under Section 853 of the Internal Revenue Code to pass through such
          taxes to shareholders as a foreign tax credit. If such election is not
          made, any foreign taxes paid or accrued will represent an expense to
          the Portfolio which will reduce its investment income.

          The Portfolio does not expect to pay any federal income or excise
          taxes because it intends to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of the Portfolio
          are sold in connection with variable insurance contracts, the
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

 14 Janus Aspen Series
<PAGE>
                                                             Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIO DIRECTLY.
          SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE INSURANCE
          CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING INSURANCE
          COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. REFER TO THE
          PROSPECTUS FOR THE PARTICIPATING INSURANCE COMPANY'S SEPARATE ACCOUNT
          OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON PURCHASING OR SELLING OF
          VARIABLE INSURANCE CONTRACTS AND ON HOW TO SELECT THE PORTFOLIO AS AN
          INVESTMENT OPTION FOR A CONTRACT OR A QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by the Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolio are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent the Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolio does not price its shares, the NAV of the Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of the Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolio's behalf.

          The Portfolio does not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. The Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of the Portfolio. Although there is no present
          intention to do so, the Portfolio may discontinue sales of its shares
          if management and the Trustees believe that continued sales may
          adversely affect the Portfolio's ability to achieve its investment
          objective. If sales of the Portfolio's Shares are discontinued, it is
          expected that existing participants invested in the Portfolio would be
          permitted to continue to authorize investment in the Portfolio and to
          reinvest any dividends or capital gains distributions, absent highly
          unusual circumstances. The Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of the Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption

                                                         Shareholder's guide  15
<PAGE>

          proceeds will normally be wired the business day following receipt of
          the redemption order, but in no event later than seven days after
          receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage the Portfolio's investments. The
          Portfolio does not permit frequent trading or market timing. When
          market timing occurs, the Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm the Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash the Portfolio will have to invest. When
          in Janus Capital's opinion such activity would have a disruptive
          effect on portfolio management, the Portfolio reserves the right to
          refuse purchase orders and exchanges into the Portfolio by any person,
          group or commonly controlled account. The Portfolio may notify a
          market timer of rejection of a purchase or exchange order after the
          day the order is placed. If the Portfolio allows a market timer to
          trade Portfolio shares, it may require the market timer to enter into
          a written agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolio that they have
          authorized for investment. Each report will show the investments owned
          by the Portfolio and the market values thereof, as well as other
          information about the Portfolio and its operations. The Trust's fiscal
          year ends December 31.

 16 Janus Aspen Series
<PAGE>
                                                            Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

                                                        Financial highlights  17
<PAGE>
Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolio may
          invest. The Portfolio may invest in these instruments to the extent
          permitted by its investment objective and policies. The Portfolio is
          not limited by this discussion and may invest in any other types of
          instruments not precluded by the policies discussed elsewhere in this
          Prospectus. Please refer to the SAI for a more detailed discussion of
          certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolio may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, the portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

 18 Janus Aspen Series
<PAGE>

          Portfolio must pay if these investments are profitable, the Portfolio
          may make various elections permitted by the tax laws. These elections
          could require that the Portfolio recognize taxable income, which in
          turn must be distributed, before the securities are sold and before
          cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by the
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, the Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by the
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by the Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

                                                Glossary of investment terms  19
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolio
          does not earn interest on such securities until settlement and bear
          the risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolio may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. It may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolio may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolio may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          The Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

 20 Janus Aspen Series
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolio may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

                                                Glossary of investment terms  21
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolio.

The Statement of Additional Information provides detailed
information about the Portfolio and is incorporated into this
Prospectus by reference. You may review the Portfolio's Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>


                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Global Life Sciences Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                Global Life Sciences Portfolio (the "Portfolio") is a mutual
                fund in Janus Aspen Series and is described in this prospectus.
                The Portfolio currently offers two classes of shares. The
                Service Shares, (the "Shares"), are offered by this prospectus
                in connection with investment in and payments under variable
                annuity contracts and variable life insurance contracts
                (collectively, "variable insurance contracts"), as well as
                certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. See the accompanying
                contract prospectus for information regarding contract fees and
                expenses and any restrictions on purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolio.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Global Life Sciences Portfolio...........................    2
                   Fees and expenses........................................    4
                INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Global Life Sciences Portfolio...........................    5
                   General portfolio policies...............................    7
                   Risks for Global Life Sciences Portfolio.................    9
                MANAGEMENT OF THE PORTFOLIO
                   Investment adviser.......................................   11
                   Management expenses and expense limits...................   11
                   Investment personnel.....................................   11
                OTHER INFORMATION...........................................   12
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   13
                   Taxes....................................................   13
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   14
                   Purchases................................................   14
                   Redemptions..............................................   14
                   Frequent trading.........................................   15
                   Shareholder communications...............................   15
                FINANCIAL HIGHLIGHTS........................................   16
                GLOSSARY
                   Glossary of investment terms.............................   17

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

GLOBAL LIFE SCIENCES PORTFOLIO

          Global Life Sciences Portfolio is designed for long-term investors who
          seek growth of capital and who can tolerate the greater risks
          associated with common stock investments.

1. WHAT IS THE INVESTMENT OBJECTIVE OF GLOBAL LIFE SCIENCES PORTFOLIO?

- --------------------------------------------------------------------------------

          - GLOBAL LIFE SCIENCES PORTFOLIO seeks long-term growth of capital.

          The Portfolio's Trustees may change this objective without a
          shareholder vote and the Portfolio will notify you of any changes that
          are material. If there is a material change to the Portfolio's
          objective or policies, you should consider whether the Portfolio
          remains an appropriate investment for you. There is no guarantee that
          the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF GLOBAL LIFE SCIENCES PORTFOLIO?

          The portfolio manager applies a "bottom up" approach in choosing
          investments. In other words, he looks for companies with earnings
          growth potential one at a time. If the portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of the Portfolio's assets may be in cash or similar investments.

          Global Life Sciences Portfolio invests primarily in equity securities
          of U.S. and foreign companies selected for their growth potential.
          Normally, it invests at least 65% of its total assets in securities of
          companies that the portfolio manager believes have a life science
          orientation. Generally speaking, the "life sciences" relate to
          maintaining or improving quality of life. So, for example, companies
          with a "life science orientation" include companies engaged in
          research, development, production or distribution of products or
          services related to health and personal care, medicine or
          pharmaceuticals. As a fundamental policy, the Portfolio normally
          invests at least 25% of its total assets, in the aggregate, in the
          following industry groups: healthcare; pharmaceuticals; agriculture;
          cosmetics/personal care; and biotechnology.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN GLOBAL LIFE SCIENCES PORTFOLIOS?

          The biggest risk of investing in this Portfolio is that its returns
          may vary, and you could lose money. If you are considering investing
          in Global Life Sciences Portfolio, remember that it is designed for
          long-term investors who can accept the risks of investing in a
          portfolio with significant common stock holdings. Common stocks tend
          to be more volatile than other investment choices.

          The value of the Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of the
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of the Portfolio's holdings decreases, the
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in the Portfolio you would get back less money.

          Global Life Sciences Portfolio concentrates its investments in related
          industry groups. Because of this, companies in its portfolio may share
          common characteristics and react similarly to market developments. For
          example, many companies with a life science orientation are highly
          regulated and may be dependent upon certain types of technology. As a
          result, changes in government funding or subsidies, new or anticipated
          legislative changes, or technological advances could affect the value
          of such companies and, therefore, the Portfolio's NAV. The Portfolio's
          returns may be more volatile than those of a less concentrated
          portfolio.

 2 Janus Aspen Series
<PAGE>

          The Portfolio may have significant exposure to foreign markets. As a
          result, its returns and NAV may be affected to a large degree by
          fluctuations in currency exchange rates or political or economic
          conditions in a particular country.

          The Portfolio is nondiversified. In other words, they may hold larger
          positions in a smaller number of securities than a diversified fund.
          As a result, a single security's increase or decrease in value may
          have a greater impact on the Portfolio's NAV and total return.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          Since Global Life Sciences Portfolio did not commence operations until
          January 15, 2000, there is no performance available as of the date of
          this prospectus.

                                                          Risk return summary  3
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolio. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of the Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolio in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>

                                                           Distribution                     Total Annual Fund
                                         Management           (12b-1)           Other           Operating
                                             Fee              Fees(1)         Expenses         Expenses(2)
    <S>                                  <C>               <C>                <C>           <C>
    Global Life Sciences Portfolio          0.65%              0.25%            0.19%             1.09%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of the Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolio with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in the Portfolio for the time
   periods indicated then redeem all of your shares at the end of those
   periods. The example also assumes that your investment has a 5% return
   each year, and that the Portfolio's operating expenses remain the same.
   Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>       <C>
    Global Life Sciences Portfolio                                 $111      $  347
</TABLE>

 4 Janus Aspen Series
<PAGE>
                                      Investment objective, principal investment
                                                 strategies and risks

          Global Life Sciences Portfolio has a similar investment objective and
          similar principal investment strategies to Janus Global Life Sciences
          Fund. Although it is anticipated that the Portfolio and Janus Global
          Life Sciences Fund will hold similar securities, differences in asset
          size, cash flow needs and other factors may result in differences in
          investment performance. The expenses of the Portfolio and Janus Global
          Life Sciences Fund are expected to differ. The variable contract owner
          will also bear various insurance related costs at the insurance
          company level. You should review the accompanying separate account
          prospectus for a summary of fees and expenses.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          This section takes a closer look at the investment objective of Global
          Life Sciences Portfolio, its principal investment strategies and
          certain risks of investing in Global Life Sciences Portfolio.
          Strategies and policies that are noted as "fundamental" cannot be
          changed without a shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 9-10 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

          Global Life Sciences Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in equity securities of
          U.S. and foreign companies selected for their growth potential.
          Normally, it invests at least 65% of its total assets in securities of
          companies that the portfolio manager believes have a life science
          orientation. As a fundamental policy, the Portfolio normally invests
          at least 25% of its total assets, in the aggregate, in the following
          industry groups: health care; pharmaceuticals; agriculture;
          cosmetics/personal care; and biotechnology.

The following questions and answers are designed to help you better understand
Global Life Sciences Portfolio's principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          The Portfolio may invest substantially all of its assets in common
          stocks if the portfolio manager believes that common stocks will
          appreciate in value. The portfolio manager generally takes a "bottom
          up" approach to selecting companies. In other words, he seeks to
          identify individual companies with earnings growth potential that may
          not be recognized by the market at large. He makes this assessment by
          looking at companies one at a time, regardless of size, country of
          organization, place of principal business activity, or other similar
          selection criteria. Realization of income is not a significant
          consideration when choosing investments for the Portfolio. Income
          realized on the Portfolio's investments may be incidental to its
          objective.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio manager seeks companies that meet his
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolio may invest and the
          Portfolio may at times have significant foreign exposure.

              Investment objective, principal investment strategies and risks  5
<PAGE>

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. Although Global Life Sciences Portfolio does
          not emphasize companies of any particular size, a Portfolio with a
          larger asset base are more likely to invest in larger, more
          established issuers.

4. WHAT DOES "LIFE SCIENCE ORIENTATION" MEAN IN RELATION TO GLOBAL LIFE SCIENCES
   PORTFOLIO?

          Generally speaking, the "life sciences" relate to maintaining or
          improving quality of life. So, for example, companies with a "life
          science orientation" include companies engaged in research,
          development, production or distribution of products or services
          related to health and personal care, medicine or pharmaceuticals. Life
          science oriented companies also include companies that the portfolio
          manager believes have growth potential primarily as a result of
          particular products, technology, patents or other market advantages in
          the life sciences. Life sciences encompass a variety of industries,
          including health care, nutrition, agriculture, medical diagnostics,
          nuclear and biochemical research and development and health care
          facilities ownership and operation.

 6 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          In investing its portfolio assets, the Portfolio will follow the
          general policies listed below. The percentage limitations included in
          these policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if the Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When the portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he is otherwise unable
          to locate attractive investment opportunities, the Portfolio's cash or
          similar investments may increase. In other words, the Portfolio does
          not always stay fully invested in stocks and bonds. Cash or similar
          investments generally are a residual - they represent the assets that
          remain after the portfolio manager has committed available assets to
          desirable investment opportunities. However, the portfolio manager may
          also temporarily increase the Portfolio's cash position to protect its
          assets or maintain liquidity.

          When the Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          Global Life Sciences Portfolio invests primarily in domestic and
          foreign equity securities, which may include preferred stocks, common
          stocks, warrants and securities convertible into common or preferred
          stocks. The Portfolio may also invest to a lesser degree in other
          types of securities. These securities (which are described in the
          Glossary) may include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of the Portfolio's assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          The Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolio's Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolio may invest without limit in foreign equity and debt
          securities. The Portfolio may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

              Investment objective, principal investment strategies and risks  7
<PAGE>

          SPECIAL SITUATIONS
          The Portfolio may invest in special situations. A special situation
          arises when, in the opinion of the Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. The Portfolio's performance
          could suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolio generally intends to purchase securities for long-term
          investment although, to a limited extent, the Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. The Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in the Portfolio's holdings whenever the
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in the Portfolio's
          performance.

 8 Janus Aspen Series
<PAGE>

RISKS FOR GLOBAL LIFE SCIENCES PORTFOLIO

          Because the Portfolio may invest substantially all of its assets in
          common stocks, the main risk is the risk that the value of the stocks
          it holds might decrease in response to the activities of an individual
          company or in response to general market and/or economic conditions.
          If this occurs, the Portfolio's share price may also decrease. The
          Portfolio's performance may also be affected by risks specific to
          certain types of investments, such as foreign securities, derivative
          investments, non-investment grade bonds, initial public offerings
          (IPOs) or companies with relatively small market capitalizations. IPOs
          and other investment techniques may have a magnified performance
          impact on a portfolio with a small asset base. A portfolio may not
          experience similar performance as its assets grow. The Portfolio's
          performance may also be affected by industry risk.

The following questions and answers are designed to help you better understand
some of the risks of investing in Global Life Sciences Portfolio.

1. THE PORTFOLIO MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF GLOBAL LIFE SCIENCES PORTFOLIO AFFECT
   ITS RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of the Portfolio.

3. HOW COULD THE PORTFOLIO'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
   PERFORMANCE?

          The Portfolio may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolio's performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as the Portfolio holds a foreign security,
            its value will be affected by the value of the local currency
            relative to the U.S. dollar. When the Portfolio sells a foreign
            denominated security, its value may be worth less in U.S. dollars
            even if the security increases in value in its home country. U.S.
            dollar denominated securities of foreign issuers may also be
            affected by currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may

              Investment objective, principal investment strategies and risks  9
<PAGE>

            take over the assets or operations of a company or that the
            government may impose taxes or limits on the removal of the
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

4. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

5. HOW DOES THE PORTFOLIO TRY TO REDUCE RISK?

          The Portfolio may use futures, options, swaps and other derivative
          instruments to "hedge" or protect its portfolio from adverse movements
          in securities prices and interest rates. The Portfolio may also use a
          variety of currency hedging techniques, including forward currency
          contracts, to manage exchange rate risk. The portfolio manager
          believes the use of these instruments will benefit the Portfolio.
          However, the Portfolio's performance could be worse than if the
          Portfolio had not used such instruments if the portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

6. WHAT IS "INDUSTRY RISK"?

          Industry risk is the possibility that a group of related stocks will
          decline in price due to industry-specific developments. Companies in
          the same or similar industries may share common characteristics and
          are more likely to react similarly to industry-specific market or
          economic developments. In the life sciences, for example, many
          companies are subject to government regulation and approval of their
          products and services, which may affect their price or availability.
          In addition, the products and services offered by these companies may
          quickly become obsolete in the face of scientific or technological
          developments. The economic outlook of such companies may fluctuate
          dramatically due to changes in regulatory or competitive environments.

          Global Life Sciences Portfolio invests in a concentrated portfolio,
          which may result in greater exposure to related industries. As a
          result, the Portfolio may be more volatile than a less concentrated
          portfolio.

 10 Janus Aspen Series
<PAGE>
                                                    Management of the portfolios

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to the Portfolio and is responsible for the
          day-to-day management of the investment portfolio and other business
          affairs of the Portfolio.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning the Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolio, and may be reimbursed by the Portfolio for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolio and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolio's Shares
          may perform certain administrative services relating to the Portfolio
          and Janus Capital or the Portfolio may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          The Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with the Portfolio
          spells out the management fee and other expenses that the Portfolio
          must pay. In addition, the Shares of the Portfolio incur expenses not
          assumed by Janus Capital, including the distribution fee, transfer
          agent and custodian fees and expenses, legal and auditing fees,
          printing and mailing costs of sending reports and other information to
          existing shareholders, and independent Trustees' fees and expenses.
          The Portfolio expects to pay Janus Capital a management fee equal to
          0.65% of average daily net assets during its initial fiscal year.
          Janus Capital has agreed to limit the Portfolio's expenses to 1.25%
          until at least the next annual renewal of the advisory agreements. The
          distribution fee described on page 12 is not included in the expense
          limit. As noted in the expense table on page 4, however, the
          Portfolio's expenses are not expected to exceed the expense limit.

INVESTMENT PERSONNEL

PORTFOLIO MANAGER

THOMAS R. MALLEY
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Global Life
            Sciences Portfolio and Janus Global Life Sciences Fund, which he
            has managed since inception. He joined Janus Capital in 1991 as a
            research analyst and has focused on companies in the health care,
            pharmaceutical and biotechnology industries. Mr. Malley has a
            Bachelor of Science in Biology from Stanford University and has
            earned the right to use the Chartered Financial Analyst
            designation.

                                                Management of the portfolios  11
<PAGE>
Other information

          CLASSES OF SHARES

          The Portfolio currently offers two classes of shares, one of which,
          the Service Shares, are offered pursuant to this prospectus. The
          Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of the
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Because the expenses of each class may
          differ, the performance of each class is expected to differ. If you
          would like additional information about the Institutional Shares,
          please call 1-800-525-0020.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of the Portfolio. Under the
          terms of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolio does not currently anticipate any disadvantages to
          owners of variable insurance contracts because the Portfolio offers
          its shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in the Portfolio or substitute Shares of
          another Portfolio. If this occurs, the Portfolio may be forced to sell
          its securities at disadvantageous prices. In addition, the Trustees
          may refuse to sell Shares of the Portfolio to any separate account or
          qualified plan or may suspend or terminate the offering of the
          Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of the Portfolio's shareholders.
          It is possible that a qualified plan investing in the Portfolio could
          lose its qualified plan status under the Internal Revenue Code, which
          could have adverse tax consequences on insurance company separate
          accounts investing in the Shares. Janus Capital intends to monitor
          such qualified plans and the Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if a plan loses (or in the
          opinion of Janus Capital is at risk of losing) its qualified plan
          status.

          DISTRIBUTION OF THE PORTFOLIO

          The Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

 12 Janus Aspen Series
<PAGE>
                                                         Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolio, the Internal Revenue Code requires
          the Portfolio to distribute net income and any net gains realized on
          its investments annually. The Portfolio's income from dividends and
          interest and any net realized short-term gains are paid to
          shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of the Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of the Portfolio will automatically be
          reinvested into additional Shares of the Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of the Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of the Portfolio's Shares. The Share price of the Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Global Life Sciences Portfolio declared a dividend in the amount of
          $0.25 per share. If the price of Global Life Sciences Portfolio's
          Shares was $10.00 on December 30, the share price on December 31 would
          be $9.75, barring market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolio may be purchased only through variable
          insurance contracts and qualified plans, it is anticipated that any
          income dividends or capital gains distributions made by the Shares of
          the Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIO

          Dividends, interest and some gains received by the Portfolio on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolio may from year to year make the election permitted
          under Section 853 of the Internal Revenue Code to pass through such
          taxes to shareholders as a foreign tax credit. If such election is not
          made, any foreign taxes paid or accrued will represent an expense to
          the Portfolio which will reduce its investment income.

          The Portfolio does not expect to pay any federal income or excise
          taxes because it intends to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of the Portfolio
          are sold in connection with variable insurance contracts, the
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  13
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIO DIRECTLY.
          SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE INSURANCE
          CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING INSURANCE
          COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. REFER TO THE
          PROSPECTUS FOR THE PARTICIPATING INSURANCE COMPANY'S SEPARATE ACCOUNT
          OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON PURCHASING OR SELLING OF
          VARIABLE INSURANCE CONTRACTS AND ON HOW TO SELECT THE PORTFOLIO AS AN
          INVESTMENT OPTION FOR A CONTRACT OR A QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by the Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolio are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent the Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolio does not price its shares, the NAV of the Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of the Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolio's behalf.

          The Portfolio does not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. The Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of the Portfolio. Although there is no present
          intention to do so, the Portfolio may discontinue sales of its shares
          if management and the Trustees believe that continued sales may
          adversely affect the Portfolio's ability to achieve its investment
          objective. If sales of the Portfolio's Shares are discontinued, it is
          expected that existing participants invested in the Portfolio would be
          permitted to continue to authorize investment in the Portfolio and to
          reinvest any dividends or capital gains distributions, absent highly
          unusual circumstances. The Portfolio may discontinue sales to a
          qualified plan and require plan participants with existing investments
          in the Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of the Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption

 14 Janus Aspen Series
<PAGE>

          proceeds will normally be wired the business day following receipt of
          the redemption order, but in no event later than seven days after
          receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage the Portfolio's investments. The
          Portfolio does not permit frequent trading or market timing. When
          market timing occurs, the Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm the Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash the Portfolio will have to invest. When
          in Janus Capital's opinion such activity would have a disruptive
          effect on portfolio management, the Portfolio reserves the right to
          refuse purchase orders and exchanges into the Portfolio by any person,
          group or commonly controlled account. The Portfolio may notify a
          market timer of rejection of a purchase or exchange order after the
          day the order is placed. If the Portfolio allows a market timer to
          trade Portfolio shares, it may require the market timer to enter into
          a written agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolio that they have
          authorized for investment. Each report will show the investments owned
          by the Portfolio and the market values thereof, as well as other
          information about the Portfolio and its operations. The Trust's fiscal
          year ends December 31.

                                                         Shareholder's guide  15
<PAGE>
Financial highlights

          No Financial Highlights are presented because the Portfolio did not
          commence operations until January 15, 2000.

 16 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolio may
          invest. The Portfolio may invest in these instruments to the extent
          permitted by its investment objective and policies. The Portfolio is
          not limited by this discussion and may invest in any other types of
          instruments not precluded by the policies discussed elsewhere in this
          Prospectus. Please refer to the SAI for a more detailed discussion of
          certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolio may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, the portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  17
<PAGE>

          Portfolio must pay if these investments are profitable, the Portfolio
          may make various elections permitted by the tax laws. These elections
          could require that the Portfolio recognize taxable income, which in
          turn must be distributed, before the securities are sold and before
          cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by the
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, the Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by the
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by the Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 18 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolio
          does not earn interest on such securities until settlement and bear
          the risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolio may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. It may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolio may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolio may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          The Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  19
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolio may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 20 Janus Aspen Series
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolio.

The Statement of Additional Information provides detailed
information about the Portfolio and is incorporated into this
Prospectus by reference. You may review the Portfolio's Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>


                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Aggressive Growth Portfolio
                              Balanced Portfolio
                              International Growth Portfolio
                              Worldwide Growth Portfolio
                              Flexible Income Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                This prospectus describes five mutual funds (the "Portfolios")
                with a variety of investment objectives, including growth of
                capital, current income and a combination of growth and income.
                Each Portfolio of Janus Aspen Series currently offers two or
                three classes of shares. The Service Shares, (the "Shares"), are
                offered by this prospectus in connection with investment in and
                payments under variable annuity contracts and variable life
                insurance contracts (collectively, "variable insurance
                contracts"), as well as certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. Certain Portfolios may not
                be available in connection with a particular contract and
                certain contracts may limit allocations among the Portfolios.
                See the accompanying contract prospectus for information
                regarding contract fees and expenses and any restrictions on
                purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolios.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Equity Portfolios........................................    2
                   Flexible Income Portfolio................................    6
                   Fees and expenses........................................    8
                INVESTMENT OBJECTIVES, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Equity Portfolios........................................    9
                   Flexible Income Portfolio................................   12
                   General portfolio policies...............................   14
                   Risks for Equity Portfolios..............................   16
                   Risks for Flexible Income Portfolio......................   17
                   Risks Common to all Portfolios...........................   17
                MANAGEMENT OF THE PORTFOLIOS
                   Investment adviser.......................................   19
                   Management expenses and expense limits...................   19
                   Investment personnel.....................................   20
                OTHER INFORMATION...........................................   22
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   24
                   Taxes....................................................   24
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   25
                   Purchases................................................   25
                   Redemptions..............................................   25
                   Frequent trading.........................................   26
                   Shareholder communications...............................   26
                FINANCIAL HIGHLIGHTS........................................   27
                GLOSSARY
                   Glossary of investment terms.............................   28
                RATING CATEGORIES
                   Explanation of rating categories.........................   32

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

EQUITY PORTFOLIOS

          The Equity Portfolios are designed for long-term investors who seek
          growth of capital and who can tolerate the greater risks associated
          with common stock investments.

1. WHAT ARE THE INVESTMENT OBJECTIVES OF THE EQUITY PORTFOLIOS?

- --------------------------------------------------------------------------------

          DOMESTIC EQUITY PORTFOLIOS

          - AGGRESSIVE GROWTH PORTFOLIO seeks long-term growth of capital.

          - BALANCED PORTFOLIO seeks long-term capital growth, consistent
            with preservation of capital and balanced by current income.

          GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          - INTERNATIONAL GROWTH PORTFOLIO seeks long-term growth of capital.

          - WORLDWIDE GROWTH PORTFOLIO seeks long-term growth of capital in a
            manner consistent with the preservation of capital.

          The Portfolios' Trustees may change these objectives without a
          shareholder vote and the Portfolios will notify you of any changes
          that are material. If there is a material change to a Portfolio's
          objective or policies, you should consider whether that Portfolio
          remains an appropriate investment for you. There is no guarantee that
          a Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF THE EQUITY PORTFOLIOS?

          The portfolio managers apply a "bottom up" approach in choosing
          investments. In other words, they look for companies with earnings
          growth potential one at a time. If a portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of a Portfolio's assets may be in cash or similar investments.

          AGGRESSIVE GROWTH PORTFOLIO invests primarily in common stocks
          selected for their growth potential, and normally invests at least 50%
          of its equity assets in medium-sized companies.

          BALANCED PORTFOLIO normally invests 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. The
          Portfolio will normally invest at least 25% of its assets in
          fixed-income securities.

          INTERNATIONAL GROWTH PORTFOLIO normally invests at least 65% of its
          total assets in securities of issuers from at least five different
          countries, excluding the United States. Although the Portfolio intends
          to invest substantially all of its assets in issuers located outside
          the United States, it may invest in U.S. issuers and it may at times
          invest all of its assets in fewer than five countries, or even a
          single country.

          WORLDWIDE GROWTH PORTFOLIO invests primarily in common stocks of
          companies of any size throughout the world. The Portfolio normally
          invests in issuers from at least five different countries, including
          the United States. The Portfolio may at times invest in fewer than
          five countries or even a single country.

 2 Janus Aspen Series
<PAGE>

3. WHAT ARE THE MAIN RISKS OF INVESTING IN THE EQUITY PORTFOLIOS?

          The biggest risk of investing in these Portfolios is that their
          returns may vary, and you could lose money. If you are considering
          investing in any of the Equity Portfolios, remember that they are each
          designed for long-term investors who can accept the risks of investing
          in a portfolio with significant common stock holdings. Common stocks
          tend to be more volatile than other investment choices.

          The value of a Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of a
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of a Portfolio's holdings decreases, that
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in a Portfolio you would get back less money.

          The income component of BALANCED PORTFOLIO includes fixed-income
          securities. A fundamental risk to the income component is that the
          value of these securities will fall if interest rates rise. Generally,
          the value of a fixed-income portfolio will decrease when interest
          rates rise, which means the Portfolio's NAV may likewise decrease.
          Another fundamental risk associated with fixed-income securities is
          credit risk, which is the risk that an issuer of a bond will be unable
          to make principal and interest payments when due.

          INTERNATIONAL GROWTH PORTFOLIO AND WORLDWIDE GROWTH PORTFOLIO may have
          significant exposure to foreign markets. As a result, their returns
          and NAV may be affected to a large degree by fluctuations in currency
          exchange rates or political or economic conditions in a particular
          country.

          AGGRESSIVE GROWTH PORTFOLIO is nondiversified. In other words, it may
          hold larger positions in a smaller number of securities than a
          diversified fund. As a result, a single security's increase or
          decrease in value may have a greater impact on a Portfolio's NAV and
          total return.

          An investment in these Portfolios is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in the Equity Portfolios by showing how each of the Equity
          Portfolios' performance has varied over time. The Portfolios' Service
          Shares commenced operations on December 31, 1999. The returns shown
          for the Service Shares of these Portfolios reflect the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses (ignoring any fee and expense
          limitations). The bar charts depict the change in performance from
          year-to-year during the period indicated but do not include charges
          and expenses attributable to any insurance product which would lower
          the performance illustrated. The Portfolios do not impose any sales or
          other charges that would affect total return computations. Total
          return figures include the effect of each Portfolio's expenses. The
          tables compare the average annual returns for the Service Shares of
          each Portfolio for the periods indicated to a broad-based securities
          market index.

                                                          Risk return summary  3
<PAGE>

           AGGRESSIVE GROWTH PORTFOLIO - SERVICE SHARES

           Annual Returns for periods ended 12/31

                             16.33%   27.38%    7.72%   12.53%   34.19%  123.16%
                              1994     1995     1996     1997     1998     1999

           Best Quarter  4th-1999  58.17%  Worst Quarter  3rd-1998 (15.00%)

                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                         1 year     5 years       (9/13/93)
                <S>                                                      <C>        <C>        <C>
                Aggressive Growth Portfolio                              123.16%    35.83%         33.98%
                S&P MidCap 400 Index*                                     14.72%    23.05%         18.08%
                                                                     ---------------------------------------------
</TABLE>

           * The S&P MidCap 400 Index is an unmanaged group of 400 domestic
             stocks chosen for their market size, liquidity and industry group
             representation.

           BALANCED PORTFOLIO - SERVICE SHARES

           Annual Returns for periods ended 12/31

                              0.84%   24.79%   16.18%   21.96%   34.03%   26.03%
                              1994     1995     1996     1997     1998     1999

           Best Quarter  4th-1998  20.26%  Worst Quarter  3rd-1998 (5.02%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Balanced Portfolio                                        26.03%    24.55%         20.51%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                Lehman Brothers Gov't/Corp Bond Index**                   (2.15%)    7.61%          5.40%
                                                                      --------------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

          ** Lehman Brothers Gov't/Corp Bond Index is composed of all bonds that
             are of investment grade with at least one year until maturity.

 4 Janus Aspen Series
<PAGE>

           INTERNATIONAL GROWTH PORTFOLIO

           Annual Returns for periods ended 12/31

                             23.15%   34.71%   18.36%   16.88%   79.52%
                              1995     1996     1997     1998     1999

           Best Quarter  4th-1999  56.24%  Worst Quarter  3rd-1998 (17.76%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                International Growth Portfolio                            79.52%    33.17%         28.19%
                Morgan Stanley Capital International EAFE(R) Index*       26.96%    12.83%         11.22%
                                                                      --------------------------------------------
</TABLE>

           * The Morgan Stanley Capital International EAFE(R) Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 20 Developed Market countries in Europe,
             Australasia and the Far East.

           WORLDWIDE GROWTH PORTFOLIO

           Annual Returns for periods ended 12/31

                              1.53%   27.29%   28.80%   21.91%   28.71%   63.49%
                              1994     1995     1996     1997     1998     1999

           Best Quarter  4th-1999  41.62%  Worst Quarter  3rd-1998 (17.00%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Worldwide Growth Portfolio                                63.49%    33.28%         29.35%
                Morgan Stanley Capital International World Index*         24.93%    19.76%         16.41%
                                                                      --------------------------------------------
</TABLE>

           * The Morgan Stanley Capital International World Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 21 Developed Market countries in North
             America, Europe and the Asia/Pacific Region.

          The Equity Portfolios' past performance does not necessarily indicate
          how they will perform in the future.

                                                          Risk return summary  5
<PAGE>

FLEXIBLE INCOME PORTFOLIO

          Flexible Income Portfolio is designed for long-term investors who
          primarily seek current income.

1. WHAT IS THE INVESTMENT OBJECTIVE OF FLEXIBLE INCOME PORTFOLIO?

- --------------------------------------------------------------------------------

          - Flexible Income Portfolio seeks to obtain maximum total return,
            consistent with preservation of capital.

          The Trustees may change the objective without a shareholder vote and
          the Portfolio will notify you of any changes that are material. If
          there is a material change to the Portfolio's objective or policies,
          you should consider whether it remains an appropriate investment for
          you. There is no guarantee that the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF FLEXIBLE INCOME PORTFOLIO?

          In addition to considering economic factors such as the effect of
          interest rates on the Portfolio's investments, the portfolio manager
          applies a "bottom up" approach in choosing investments. In other
          words, he looks mostly for income-producing securities that meet its
          investment criteria one at a time. If the portfolio manager is unable
          to find such investments, the Portfolio's assets may be in cash or
          similar investments.

          Flexible Income Portfolio invests primarily in a wide variety of
          income-producing securities such as corporate bonds and notes,
          government securities and preferred stock. As a fundamental policy,
          the Portfolio will invest at least 80% of its assets in
          income-producing securities. The Portfolio may own an unlimited amount
          of high-yield/high-risk bonds, and these securities may be a big part
          of the portfolio.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN FLEXIBLE INCOME PORTFOLIO?

          Although Flexible Income Portfolio may be less volatile than funds
          that invest most of their assets in common stocks, the Portfolio's
          returns and yields will vary, and you could lose money.

          The Portfolio invests in a variety of fixed-income securities. A
          fundamental risk is that the value of these securities will fall if
          interest rates rise. Generally, the value of a fixed-income portfolio
          will decrease when interest rates rise, which means the Portfolio's
          NAV will likewise decrease. Another fundamental risk associated with
          fixed-income funds is credit risk, which is the risk that an issuer
          will be unable to make principal and interest payments when due.

          Flexible Income Portfolio may invest an unlimited amount of its assets
          in high-yield/high-risk bonds, also known as "junk" bonds which may be
          sensitive to economic changes, political changes, or adverse
          developments specific to the company that issued the bond. These bonds
          generally have a greater credit risk than other types of fixed-income
          securities. Because of these factors, the performance and NAV of
          Flexible Income Portfolio may vary significantly, depending upon its
          holdings of junk bonds.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

 6 Janus Aspen Series
<PAGE>

          The following information provides some indication of the risks of
          investing in Flexible Income Portfolio by showing how Flexible Income
          Portfolio's performance has varied over time. The Portfolio's Service
          Shares commenced operations on December 31, 1999. The returns shown
          for the Service Shares of the Portfolio reflect the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses on (ignoring any fee and expense
          limitations). The bar chart depicts the change in performance from
          year-to-year during the period indicated but does not include charges
          and expenses attributable to any insurance product which would lower
          the performance illustrated. The Portfolio does not impose any sales
          or other charges that would affect total return computations. Total
          return figures include the effect of the Portfolio's expenses. The
          table compares the average annual returns for the Service Shares of
          the Portfolio for the periods indicated to a broad-based securities
          market index.

           FLEXIBLE INCOME PORTFOLIO

           Annual Returns for periods ended 12/31

                            (0.91%)   23.86%    9.03%   11.52%    8.85%    1.30%
                              1994     1995     1996     1997     1998     1999

           Best Quarter  2nd-1995  6.71%  Worst Quarter  2nd-1999 (1.27%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Flexible Income Portfolio                                  1.30%    10.68%          8.36%
                Lehman Brothers Gov't/Corp Bond Index*                    (2.15%)    7.61%          5.40%
                                                                      --------------------------------------------
</TABLE>

           * Lehman Brothers Gov't/Corp Bond Index is composed of all bonds that
             are of investment grade with at least one year until maturity.

          Flexible Income Portfolio's past performance does not necessarily
          indicate how it will perform in the future.

                                                          Risk return summary  7
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolios. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of a Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolios in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. The information shown is based upon estimated gross
          expenses (without the effect of expense offset arrangements) the
          Shares expect to incur in their initial fiscal year. OWNERS OF
          VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE SHARES SHOULD REFER TO
          THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR A DESCRIPTION OF FEES
          AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT REFLECT DEDUCTIONS AT
          THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR ANY CHARGES THAT MAY
          BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                      Distribution                    Total Annual Fund
                                      Management         (12b-1)          Other           Operating
                                          Fee            Fees(1)         Expenses         Expenses(2)
    <S>                               <C>             <C>                <C>          <C>
    Aggressive Growth Portfolio          0.65%            0.25%           0.02%             0.92%
    Balanced Portfolio                   0.65%            0.25%           0.02%             0.92%
    International Growth Portfolio       0.65%            0.25%           0.11%             1.01%
    Worldwide Growth Portfolio           0.65%            0.25%           0.05%             0.95%
    Flexible Income Portfolio            0.65%            0.25%           0.07%             0.97%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of each Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolios with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in each of the Portfolios for
   the time periods indicated then redeem all of your shares at the end of
   those periods. The example also assumes that your investment has a 5%
   return each year, and that the Portfolios' operating expenses remain the
   same. Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Aggressive Growth Portfolio                                    $ 94       $293
    Balanced Portfolio                                             $ 94       $293
    International Growth Portfolio                                 $103       $322
    Worldwide Growth Portfolio                                     $ 97       $303
    Flexible Income Portfolio                                      $ 99       $309
</TABLE>

 8 Janus Aspen Series
<PAGE>
                                     Investment objectives, principal investment
                                                strategies and risks

          Each of the Portfolios has a similar investment objective and similar
          principal investment strategies to a Janus retail fund:

<TABLE>
                  <S>                                    <C>
                  Aggressive Growth Portfolio                 Janus Enterprise Fund
                  Balanced Portfolio                            Janus Balanced Fund
                  International Growth Portfolio                Janus Overseas Fund
                  Worldwide Growth Portfolio                   Janus Worldwide Fund
                  Flexible Income Portfolio              Janus Flexible Income Fund
</TABLE>

          Although it is anticipated that each Portfolio and its corresponding
          retail fund will hold similar securities, differences in asset size,
          cash flow needs and other factors may result in differences in
          investment performance. The expenses of each Portfolio and its
          corresponding retail fund are expected to differ. The variable
          contract owner will also bear various insurance related costs at the
          insurance company level. You should review the accompanying separate
          account prospectus for a summary of fees and expenses.

EQUITY PORTFOLIOS

          This section takes a closer look at the investment objectives of each
          of the Equity Portfolios, their principal investment strategies and
          certain risks of investing in the Equity Portfolios. Strategies and
          policies that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 16-18 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

INVESTMENT OBJECTIVES AND PRINCIPAL INVESTMENT STRATEGIES

DOMESTIC EQUITY PORTFOLIOS

          AGGRESSIVE GROWTH PORTFOLIO
          Aggressive Growth Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential, and normally invests at least 50% of its
          equity assets in medium-sized companies. Medium-sized companies are
          those whose market capitalization falls within the range of companies
          in the S&P MidCap 400 Index. Market capitalization is a commonly used
          measure of the size and value of a company. The market capitalizations
          within the Index will vary, but as of December 31, 1999, they ranged
          from approximately $170 million to $37 billion.

          BALANCED PORTFOLIO
          Balanced Portfolio seeks long-term capital growth, consistent with
          preservation of capital and balanced by current income. It pursues its
          objective by normally investing 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. This
          Portfolio normally invests at least 25% of its assets in fixed-income
          securities.

             Investment objectives, principal investment strategies and risks  9
<PAGE>

GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          INTERNATIONAL GROWTH PORTFOLIO
          International Growth Portfolio seeks long-term growth of capital.
          Normally, the Portfolio pursues its objective by investing at least
          65% of its total assets in securities of issuers from at least five
          different countries, excluding the United States. Although the
          Portfolio intends to invest substantially all of its assets in issuers
          located outside the United States, it may at times invest in U.S.
          issuers and it may at times invest all of its assets in fewer than
          five countries or even a single country.

          WORLDWIDE GROWTH PORTFOLIO
          Worldwide Growth Portfolio seeks long-term growth of capital in a
          manner consistent with the preservation of capital. It pursues its
          objective by investing primarily in common stocks of companies of any
          size throughout the world. The Portfolio normally invests in issuers
          from at least five different countries, including the United States.
          The Portfolio may at times invest in fewer than five countries or even
          a single country.

The following questions and answers are designed to help you better understand
the Equity Portfolios' principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          Each of the Portfolios may invest substantially all of its assets in
          common stocks if its portfolio manager believes that common stocks
          will appreciate in value. The portfolio managers generally take a
          "bottom up" approach to selecting companies. In other words, they seek
          to identify individual companies with earnings growth potential that
          may not be recognized by the market at large. They make this
          assessment by looking at companies one at a time, regardless of size,
          country of organization, place of principal business activity, or
          other similar selection criteria. Except for Balanced Portfolio,
          realization of income is not a significant consideration when choosing
          investments for the Portfolios. Income realized on the Portfolios'
          investments may be incidental to their objectives. In the case of
          Balanced Portfolio, the portfolio manager may consider dividend-paying
          characteristics to a greater degree in selecting common stock.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio managers seek companies that meet their
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolios may invest and
          the Portfolios may at times have significant foreign exposure.

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. As noted previously, market capitalization is
          an important investment criteria for Aggressive Growth Portfolio.
          Although the other Equity Portfolios offered by this Prospectus do not
          emphasize companies of any particular size, Portfolios with a larger
          asset base are more likely to invest in larger, more established
          issuers.

 10 Janus Aspen Series
<PAGE>

4. HOW ARE ASSETS ALLOCATED BETWEEN THE GROWTH AND INCOME COMPONENTS OF BALANCED
   PORTFOLIO'S HOLDINGS?

          Balanced Portfolio shifts assets between the growth and income
          components of its holdings based on the portfolio manager's analysis
          of relevant market, financial and economic conditions. If the
          portfolio manager believes that growth securities will provide better
          returns than the yields then available or expected on income-producing
          securities, the Portfolio will place a greater emphasis on the growth
          component.

5. WHAT TYPES OF SECURITIES MAKE UP THE GROWTH COMPONENT OF BALANCED PORTFOLIO'S
   INVESTMENTS?

          The growth component of Balanced Portfolio is expected to consist
          primarily of common stocks, but may also include warrants, preferred
          stocks or convertible securities selected primarily for their growth
          potential.

6. WHAT TYPES OF SECURITIES MAKE UP THE INCOME COMPONENT OF BALANCED PORTFOLIO'S
   HOLDINGS?

          The income component of Balanced Portfolio is expected to consist of
          securities that the portfolio manager believes have income potential.
          Such securities may include equity securities, convertible securities
          and all types of debt securities. Equity securities may be included in
          the income component of the Portfolio if they currently pay dividends
          or the portfolio manager believes they have the potential for either
          increasing their dividends or commencing dividends, if none are
          currently paid.

            Investment objectives, principal investment strategies and risks  11
<PAGE>

FLEXIBLE INCOME PORTFOLIO

          This section takes a closer look at the investment objective of
          Flexible Income Portfolio, its principal investment strategies and
          certain risks of investing in the Portfolio. Strategies and policies
          that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 17-18 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          In addition to considering economic factors such as the effect of
          interest rates on the Portfolio's investments, the portfolio manager
          applies a "bottom up" approach in choosing investments. In other
          words, he looks mostly for income-producing securities that meet his
          investment criteria one at a time. If the portfolio manager is unable
          to find such investments, much of the Portfolio's assets may be in
          cash or similar investments.

          Flexible Income Portfolio seeks to obtain maximum total return,
          consistent with preservation of capital. It pursues its objective by
          primarily investing in a wide variety of income-producing securities
          such as corporate bonds and notes, government securities and preferred
          stock. As a fundamental policy, the Portfolio will invest at least 80%
          of its assets in income-producing securities. The Portfolio may own an
          unlimited amount of high-yield/high-risk bonds, and these may be a big
          part of the portfolio. This Portfolio generates total return from a
          combination of current income and capital appreciation, but income is
          usually the dominant portion.

The following questions and answers are designed to help you better understand
Flexible Income Portfolio's principal investment strategies.

1. HOW DO INTEREST RATES AFFECT THE VALUE OF MY INVESTMENT?

          Generally, a fixed-income security will increase in value when
          interest rates fall and decrease in value when interest rates rise.
          Longer-term securities are generally more sensitive to interest rate
          changes than shorter-term securities, but they generally offer higher
          yields to compensate investors for the associated risks. High-yield
          bond prices are generally less directly responsive to interest rate
          changes than investment grade issues and may not always follow this
          pattern. A bond fund's average-weighted effective maturity and its
          duration are measures of how the fund may react to interest rate
          changes.

2. HOW DOES FLEXIBLE INCOME PORTFOLIO MANAGE INTEREST RATE RISK?

          Flexible Income Portfolio may vary the average-weighted effective
          maturity of its assets to reflect its portfolio manager's analysis of
          interest rate trends and other factors. The Portfolio's
          average-weighted effective maturity will tend to be shorter when the
          portfolio manager expects interest rates to rise and longer when the
          portfolio manager expects interest rates to fall. The Portfolio may
          also use futures, options and other derivatives to manage interest
          rate risks.

3. WHAT IS MEANT BY THE PORTFOLIO'S "AVERAGE-WEIGHTED EFFECTIVE MATURITY"?

          The stated maturity of a bond is the date when the issuer must repay
          the bond's entire principal value to an investor. Some types of bonds
          may also have an "effective maturity" that is shorter than the stated
          date due to prepayment or call provisions. Securities without
          prepayment or call provisions generally have an effective maturity
          equal to their stated maturity. Dollar-weighted effective maturity is
          calculated by

 12 Janus Aspen Series
<PAGE>

          averaging the effective maturity of bonds held by the Portfolio with
          each effective maturity "weighted" according to the percentage of net
          assets that it represents.

4. WHAT IS MEANT BY THE PORTFOLIO'S "DURATION"?

          A bond's duration indicates the time it will take an investor to
          recoup his investment. Unlike average maturity, duration reflects both
          principal and interest payments. Generally, the higher the coupon rate
          on a bond, the lower its duration will be. The duration of a bond
          portfolio is calculated by averaging the duration of bonds held by a
          fund with each duration "weighted" according to the percentage of net
          assets that it represents. Because duration accounts for interest
          payments, the Portfolio's duration is usually shorter than its average
          maturity.

5. WHAT IS A HIGH-YIELD/HIGH-RISK BOND?

          A high-yield/high-risk bond (also called a "junk" bond) is a bond
          rated below investment grade by major rating agencies (i.e., BB or
          lower by Standard & Poor's or Ba or lower by Moody's) or an unrated
          bond of similar quality. It presents greater risk of default (the
          failure to make timely interest and principal payments) than higher
          quality bonds.

            Investment objectives, principal investment strategies and risks  13
<PAGE>

GENERAL PORTFOLIO POLICIES

          Unless otherwise stated, each of the following policies applies to all
          of the Portfolios. The percentage limitations included in these
          policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if a Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When a portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he or she is otherwise
          unable to locate attractive investment opportunities, the Portfolios'
          cash or similar investments may increase. In other words, the
          Portfolios do not always stay fully invested in stocks and bonds. Cash
          or similar investments generally are a residual - they represent the
          assets that remain after a portfolio manager has committed available
          assets to desirable investment opportunities. However, a portfolio
          manager may also temporarily increase a Portfolio's cash position to
          protect its assets or maintain liquidity. Partly because the portfolio
          managers act independently of each other, the cash positions of the
          Portfolios may vary significantly.

          When a Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          The Equity Portfolios invest primarily in domestic and foreign equity
          securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Equity Portfolios also invest in domestic and foreign equity
          securities with varying degrees of emphasis on income. The Portfolios
          may also invest to a lesser degree in other types of securities. These
          securities (which are described in the Glossary) may include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of each Portfolio's
            assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          Flexible Income Portfolio invests primarily in fixed-income securities
          which may include corporate bonds and notes, government securities,
          preferred stock, high-yield/high-risk fixed-income securities and
          municipal obligations. The Portfolio may also invest to a lesser
          degree in other types of securities. These securities (which are
          described in the Glossary) may include:

          - common stocks

          - mortgage- and asset-backed securities

          - zero coupon, pay-in-kind and step coupon securities

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

 14 Janus Aspen Series
<PAGE>

          ILLIQUID INVESTMENTS
          Each Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolios' Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolios may invest without limit in foreign equity and debt
          securities. The Portfolios may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

          SPECIAL SITUATIONS
          Each Portfolio may invest in special situations. A special situation
          arises when, in the opinion of a Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. A Portfolio's performance could
          suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolios generally intend to purchase securities for long-term
          investment although, to a limited extent, a Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. A Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in a Portfolio's holdings whenever its
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in a Portfolio's
          performance.

            Investment objectives, principal investment strategies and risks  15
<PAGE>

RISKS FOR EQUITY PORTFOLIOS

          Because the Portfolios may invest substantially all of their assets in
          common stocks, the main risk is the risk that the value of the stocks
          they hold might decrease in response to the activities of an
          individual company or in response to general market and/or economic
          conditions. If this occurs, a Portfolio's share price may also
          decrease. A Portfolio's performance may also be affected by risks
          specific to certain types of investments, such as foreign securities,
          derivative investments, non-investment grade debt securities, initial
          public offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in the Equity Portfolios.

1. THE PORTFOLIOS MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF AGGRESSIVE GROWTH PORTFOLIO AFFECT ITS
   RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of the Portfolio.

 16 Janus Aspen Series
<PAGE>

RISKS FOR FLEXIBLE INCOME PORTFOLIO

          Because the Portfolio invests substantially all of its assets in
          fixed-income securities, it is subject to risks such as credit or
          default risks, and decreased value due to interest rate increases. The
          Portfolio's performance may also be affected by risks to certain types
          of investments, such as foreign securities, derivative instruments and
          initial public offerings (IPOs). IPOs and other investment techniques
          may have a magnified performance impact on a portfolio with a small
          asset base. A portfolio may not experience similar performance as its
          assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in Flexible Income Portfolio.

1. WHAT IS MEANT BY "CREDIT QUALITY" AND WHAT ARE THE RISKS ASSOCIATED WITH IT?

          Credit quality measures the likelihood that the issuer will meet its
          obligations on a bond. One of the fundamental risks associated with
          all fixed-income funds is credit risk, which is the risk that an
          issuer will be unable to make principal and interest payments when
          due. U.S. government securities are generally considered to be the
          safest type of investment in terms of credit risk. Municipal
          obligations generally rank between U.S. government securities and
          corporate debt securities in terms of credit safety. Corporate debt
          securities, particularly those rated below investment grade, present
          the highest credit risk.

2. HOW IS CREDIT QUALITY MEASURED?

          Ratings published by nationally recognized statistical rating agencies
          such as Standard & Poor's Ratings Service and Moody's Investors
          Service, Inc. are widely accepted measures of credit risk. The lower a
          bond issue is rated by an agency, the more credit risk it is
          considered to represent. Lower rated bonds generally pay higher yields
          to compensate investors for the associated risk. Please refer to
          "Explanation of Rating Categories" on pages 32-33 for a description of
          rating categories.

RISKS COMMON TO ALL PORTFOLIOS

The following questions and answers discuss risks that apply to all Portfolios.

1. HOW COULD THE PORTFOLIOS' INVESTMENTS IN FOREIGN SECURITIES AFFECT THEIR
   PERFORMANCE?

          The Portfolios may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolios' performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as a Portfolio holds a foreign security, its
            value will be affected by the value of the local currency relative
            to the U.S. dollar. When a Portfolio sells a foreign denominated
            security, its value may be worth less in U.S. dollars even if the
            security increases in value in its home country. U.S. dollar
            denominated securities of foreign issuers may also be affected by
            currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may take over the assets or operations of a company or
            that the government may impose taxes or limits on the removal of a
            Portfolio's assets from that country.

            Investment objectives, principal investment strategies and risks  17
<PAGE>

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

2. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          The junk bond market can experience sudden and sharp price swings.
          Because Flexible Income Portfolio may invest a significant portion of
          its assets in high-yield/high-risk bonds, investors should be willing
          to tolerate a corresponding increase in the risk of significant and
          sudden changes in NAV.

          Please refer to "Explanation of Rating Categories" on pages 32-33 for
          a description of bond rating categories.

3. HOW DO THE PORTFOLIOS TRY TO REDUCE RISK?

          The Portfolios may use futures, options, swaps and other derivative
          instruments to "hedge" or protect their portfolios from adverse
          movements in securities prices and interest rates. The Portfolios may
          also use a variety of currency hedging techniques, including forward
          currency contracts, to manage exchange rate risk. The portfolio
          managers believe the use of these instruments will benefit the
          Portfolios. However, a Portfolio's performance could be worse than if
          the Portfolio had not used such instruments if a portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 18 Janus Aspen Series
<PAGE>
                                                    Management of the portfolios

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to each of the Portfolios and is responsible
          for the day-to-day management of the investment portfolios and other
          business affairs of the Portfolios.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning each Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolios, and may be reimbursed by the Portfolios for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolios and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolios' Shares
          may perform certain administrative services relating to the Portfolios
          and Janus Capital or the Portfolios may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          Each Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with each Portfolio
          spells out the management fee and other expenses that the Portfolios
          must pay. Each of the Portfolios is subject to the following
          management fee schedule (expressed as an annual rate). In addition,
          the Shares of each Portfolio incur expenses not assumed by Janus
          Capital, including the distribution fee, transfer agent and custodian
          fees and expenses, legal and auditing fees, printing and mailing costs
          of sending reports and other information to existing shareholders, and
          independent Trustees' fees and expenses.

<TABLE>
<CAPTION>
                                                          Average Daily
                                                           Net Assets         Annual Rate      Expense Limit
     Fee Schedule                                         of Portfolio       Percentage (%)    Percentage (%)
- ------------------------------------------------------------------------------------------------------------------
<S>                                                     <C>                  <C>               <C>
     Aggressive Growth Portfolio                         All Asset Levels         0.65               N/A
     Balanced Portfolio
     International Growth Portfolio
     Worldwide Growth Portfolio
- ------------------------------------------------------------------------------------------------------------------
     Flexible Income Portfolio                          First $300 Million        0.65              1.00(1)
                                                        Over $300 Million         0.55
- ------------------------------------------------------------------------------------------------------------------
</TABLE>

(1) Janus Capital has agreed to limit the Portfolio's expenses as indicated
    until at least the next annual renewal of the advisory agreements. As noted
    in the fee table on page 8, however, the Portfolio's expenses without
    waivers are not expected to exceed the expense limit.

          For the fiscal year ended December 31, 1999, each Portfolio paid Janus
          Capital the following management fees based upon each Portfolio's
          average net assets: 0.68% for Aggressive Growth Portfolio, 0.67% for
          Balanced Portfolio, 0.73% for International Growth Portfolio, 0.66%
          for Worldwide Growth Portfolio and 0.65% for Flexible Income
          Portfolio. These rates were based on a higher fee rate that was
          previously in effect for certain of these Portfolios.

                                                Management of the portfolios  19
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGERS

LAURENCE J. CHANG
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio which he has
            co-managed since May 1998 and December 1999, respectively. He has
            also co-managed Janus Overseas Fund and Janus Worldwide Fund
            since April 1998 and September 1999, respectively. He served as
            assistant portfolio manager for these funds since 1996. Mr. Chang
            joined Janus Capital in 1993 as a research analyst. He received
            an undergraduate degree with honors in Religion with a
            concentration in Philosophy from Dartmouth College and a Masters
            Degree in Political Science from Stanford University. He has
            earned the right to use the Chartered Financial Analyst
            designation.

JAMES P. GOFF
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Aggressive
            Growth Portfolio, which he has managed since inception. Mr. Goff
            joined Janus Capital in 1988 and has managed Janus Enterprise
            Fund since its inception. Mr. Goff co-managed or managed Janus
            Venture Fund from December 1993 to February 1997. He holds a
            Bachelor of Arts in Economics from Yale University and he has
            earned the right to use the Chartered Financial Analyst
            designation.

HELEN YOUNG HAYES
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio, which she has
            managed or co-managed since inception. Ms. Hayes joined Janus
            Capital in 1987 and has managed or co-managed Janus Worldwide
            Fund and Janus Overseas Fund since their inceptions. She holds a
            Bachelor of Arts in Economics from Yale University and she has
            earned the right to use the Chartered Financial Analyst
            designation.

KAREN L. REIDY
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Balanced
            Portfolio and Equity Income Portfolio as of January 2000, and an
            assistant portfolio manager of Growth Portfolio since 1998. She
            also manages Janus Balanced Fund and Janus Equity Income Fund as
            of January 2000. She is also assistant portfolio manager of Janus
            Fund. Prior to joining Janus Capital in 1995, she worked for
            Price Waterhouse as a manager in both the Mergers and
            Acquisitions and Audit business units. In this capacity, Ms.
            Reidy performed due diligence work for corporate clients and
            oversaw audit engagements. She received an undergraduate degree
            in Accounting from the University of Colorado in 1989 and passed
            the CPA exam in 1992. She has earned the right to use the
            Chartered Financial Analyst designation.

 20 Janus Aspen Series
<PAGE>

RONALD V. SPEAKER
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Flexible
            Income Portfolio which he has managed or co-managed since its
            inception. He previously served as co-manager of High-Yield
            Portfolio, from its inception to May 1998. He managed Short-Term
            Bond Portfolio from its inception through April 1996. Mr. Speaker
            joined Janus Capital in 1986. He has managed or co-managed Janus
            Flexible Income Fund since December 1991 and previously managed
            both Janus Short-Term Bond Fund and Janus Federal Tax-Exempt Fund
            from inception through December 1995. He previously managed or
            co-managed Janus High-Yield Fund from its inception to February
            1998. He holds a Bachelor of Arts in Finance from the University
            of Colorado and he has earned the right to use the Chartered
            Financial Analyst designation.

            In January 1997, Mr. Speaker settled an SEC administrative action
            involving two personal trades made by him in January of 1993.
            Without admitting or denying the allegations, Mr. Speaker agreed
            to civil money penalty, disgorgement, and interest payments
            totaling $37,199 and to a 90-day suspension which ended on April
            25, 1997.

ASSISTANT PORTFOLIO MANAGERS

MATTHEW A. ANKRUM
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            He is also assistant portfolio manager of Janus Enterprise Fund.
            Mr. Ankrum joined Janus Capital as an intern in June 1996, and
            became an equity research analyst in August 1997. Prior to
            joining Janus, Mr. Ankrum worked as a corporate finance analyst
            at William Blair and Company from 1993 through 1995. He was also
            a fixed-income research analyst at Conseco Capital Management.
            Mr. Ankrum has an undergraduate degree in Business Administration
            from the University of Wisconsin and a Master of Business
            Administration from the University of Chicago. Mr. Ankrum has
            earned the right to use the Chartered Financial Analyst
            designation.

RON SACHS
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            Mr. Sachs joined Janus Capital in 1996 as a research analyst.
            Prior to coming to Janus, he worked as a consultant for Bain &
            Company and as an attorney for Willkie, Farr & Gallagher. Mr.
            Sachs graduated from Princeton cum laude with an undergraduate
            degree in economics. He obtained his law degree from the
            University of Michigan. Mr. Sachs has earned the right to use the
            Chartered Financial Analyst designation.

                                                Management of the portfolios  21
<PAGE>
Other information

          CLASSES OF SHARES

          Each Portfolio currently offers two or three classes of shares, one of
          which, the Service Shares, are offered pursuant to this prospectus.
          The Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of each
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of certain Portfolios
          are offered only to qualified plans using plan service providers that
          are compensated for providing distribution and/or record keeping and
          other administrative services provided to plan participants. Because
          the expenses of each class may differ, the performance of each class
          is expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, each Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of a Portfolio. Under the terms
          of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolios do not currently anticipate any disadvantages to owners
          of variable insurance contracts because each Portfolio offers its
          shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in one or more Portfolios or substitute
          Shares of another Portfolio. If this occurs, a Portfolio may be forced
          to sell its securities at disadvantageous prices. In addition, the
          Trustees may refuse to sell Shares of any Portfolio to any separate
          account or qualified plan or may suspend or terminate the offering of
          a Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of that Portfolio's
          shareholders. It is possible that a qualified plan investing in the
          Portfolios could lose its qualified plan status under the Internal
          Revenue Code, which could have adverse tax consequences on insurance
          company separate accounts investing in the Shares. Janus Capital
          intends to monitor such qualified plans and the Portfolios may
          discontinue sales to a qualified plan and require plan participants
          with existing investments in the Shares to redeem those investments if
          a plan loses (or in the opinion of Janus Capital is at risk of losing)
          its qualified plan status.

 22 Janus Aspen Series
<PAGE>

          DISTRIBUTION OF EACH PORTFOLIO

          Each Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

                                                           Other information  23
<PAGE>
Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolios, the Internal Revenue Code
          requires each Portfolio to distribute net income and any net gains
          realized on its investments annually. A Portfolio's income from
          dividends and interest and any net realized short-term gains are paid
          to shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of each Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of a Portfolio will automatically be
          reinvested into additional Shares of that Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions, other than daily income dividends, are paid to
          shareholders as of the record date of the distribution of a Portfolio,
          regardless of how long the shares have been held. Undistributed income
          and realized gains are included in the daily NAV of a Portfolio's
          Shares. The Share price of a Portfolio drops by the amount of the
          distribution, net of any subsequent market fluctuations. For example,
          assume that on December 31, the Shares of Aggressive Growth Portfolio
          declared a dividend in the amount of $0.25 per share. If the price of
          Aggressive Growth Portfolio's Shares was $10.00 on December 30, the
          share price on December 31 would be $9.75, barring market
          fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolios may be purchased only through
          variable insurance contracts and qualified plans, it is anticipated
          that any income dividends or capital gains distributions made by the
          Shares of a Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIOS

          Dividends, interest and some gains received by the Portfolios on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolios may from year to year make the election
          permitted under Section 853 of the Internal Revenue Code to pass
          through such taxes to shareholders as a foreign tax credit. If such
          election is not made, any foreign taxes paid or accrued will represent
          an expense to the Portfolios which will reduce their investment
          income.

          The Portfolios do not expect to pay any federal income or excise taxes
          because they intend to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of each Portfolio
          are sold in connection with variable insurance contracts, each
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

 24 Janus Aspen Series
<PAGE>
                                                             Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIOS
          DIRECTLY. SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE
          INSURANCE CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING
          INSURANCE COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. CERTAIN
          PORTFOLIOS MAY NOT BE AVAILABLE IN CONNECTION WITH A PARTICULAR
          CONTRACT AND CERTAIN CONTRACTS MAY LIMIT ALLOCATIONS AMONG THE
          PORTFOLIOS. REFER TO THE PROSPECTUS FOR THE PARTICIPATING INSURANCE
          COMPANY'S SEPARATE ACCOUNT OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON
          PURCHASING OR SELLING OF VARIABLE INSURANCE CONTRACTS AND ON HOW TO
          SELECT SPECIFIC PORTFOLIOS AS INVESTMENT OPTIONS FOR A CONTRACT OR A
          QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by a Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolios are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent a Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolios do not price their shares, the NAV of a Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of each Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolios' behalf.

          The Portfolios do not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. Each Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of a Portfolio. Although there is no present intention
          to do so, the Portfolios may discontinue sales of their shares if
          management and the Trustees believe that continued sales may adversely
          affect a Portfolio's ability to achieve its investment objective. If
          sales of a Portfolio's Shares are discontinued, it is expected that
          existing participants invested in that Portfolio would be permitted to
          continue to authorize investment in that Portfolio and to reinvest any
          dividends or capital gains distributions, absent highly unusual
          circumstances. The Portfolios may discontinue sales to a qualified
          plan and require plan participants with existing investments in the
          Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

                                                         Shareholder's guide  25
<PAGE>

          Shares of any Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption proceeds will normally be wired the business day following
          receipt of the redemption order, but in no event later than seven days
          after receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage a Portfolio's investments. The
          Portfolios do not permit frequent trading or market timing. When
          market timing occurs, a Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm a Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash a Portfolio will have to invest. When in
          Janus Capital's opinion such activity would have a disruptive effect
          on portfolio management, a Portfolio reserves the right to refuse
          purchase orders and exchanges into a Portfolio by any person, group or
          commonly controlled account. A Portfolio may notify a market timer of
          rejection of a purchase or exchange order after the day the order is
          placed. If a Portfolio allows a market timer to trade Portfolio
          shares, it may require the market timer to enter into a written
          agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolios that they have
          authorized for investment. Each report will show the investments owned
          by each Portfolio and the market values thereof, as well as other
          information about the Portfolios and their operations. The Trust's
          fiscal year ends December 31.

 26 Janus Aspen Series
<PAGE>
                                                            Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

                                                        Financial highlights  27
<PAGE>
Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolios may
          invest. The Portfolios may invest in these instruments to the extent
          permitted by their investment objectives and policies. The Portfolios
          are not limited by this discussion and may invest in any other types
          of instruments not precluded by the policies discussed elsewhere in
          this Prospectus. Please refer to the SAI for a more detailed
          discussion of certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolios may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, a portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

 28 Janus Aspen Series
<PAGE>

          Portfolios must pay if these investments are profitable, the
          Portfolios may make various elections permitted by the tax laws. These
          elections could require that the Portfolios recognize taxable income,
          which in turn must be distributed, before the securities are sold and
          before cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by a
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, a Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by a
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by a Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

                                                Glossary of investment terms  29
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolios do
          not earn interest on such securities until settlement and bear the
          risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolios may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. They may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolios may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolios may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          A Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

 30 Janus Aspen Series
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolios may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

                                                Glossary of investment terms  31
<PAGE>
Explanation of rating categories

          The following is a description of credit ratings issued by two of the
          major credit ratings agencies. Credit ratings evaluate only the safety
          of principal and interest payments, not the market value risk of lower
          quality securities. Credit rating agencies may fail to change credit
          ratings to reflect subsequent events on a timely basis. Although Janus
          Capital considers security ratings when making investment decisions,
          it also performs its own investment analysis and does not rely solely
          on the ratings assigned by credit agencies.

STANDARD & POOR'S
RATINGS SERVICES

<TABLE>
                <S>                          <C>
                BOND RATING                  EXPLANATION
                -----------------------------------------------------------------------------------------
                Investment Grade
                AAA......................... Highest rating; extremely strong capacity to pay principal
                                             and interest.
                AA.......................... High quality; very strong capacity to pay principal and
                                             interest.
                A........................... Strong capacity to pay principal and interest; somewhat more
                                             susceptible to the adverse effects of changing circumstances
                                             and economic conditions.
                BBB......................... Adequate capacity to pay principal and interest; normally
                                             exhibit adequate protection parameters, but adverse economic
                                             conditions or changing circumstances more likely to lead to
                                             a weakened capacity to pay principal and interest than for
                                             higher rated bonds.
                Non-Investment Grade
                BB, B, CCC, CC, C........... Predominantly speculative with respect to the issuer's
                                             capacity to meet required interest and principal payments.
                                             BB - lowest degree of speculation; C - the highest degree of
                                             speculation. Quality and protective characteristics
                                             outweighed by large uncertainties or major risk exposure to
                                             adverse conditions.
                D........................... In default.
</TABLE>

 32 Janus Aspen Series
<PAGE>

MOODY'S INVESTORS SERVICE, INC.

<TABLE>
                <S>                          <C>
                BOND RATING                  EXPLANATION
                -----------------------------------------------------------------------------------------
                Investment Grade
                Aaa......................... Highest quality, smallest degree of investment risk.
                Aa.......................... High quality; together with Aaa bonds, they compose the
                                             high-grade bond group.
                A........................... Upper-medium grade obligations; many favorable investment
                                             attributes.
                Baa......................... Medium-grade obligations; neither highly protected nor
                                             poorly secured. Interest and principal appear adequate for
                                             the present but certain protective elements may be lacking
                                             or may be unreliable over any great length of time.
                Non-Investment Grade
                Ba.......................... More uncertain, with speculative elements. Protection of
                                             interest and principal payments not well safeguarded during
                                             good and bad times.
                B........................... Lack characteristics of desirable investment; potentially
                                             low assurance of timely interest and principal payments or
                                             maintenance of other contract terms over time.
                Caa......................... Poor standing, may be in default; elements of danger with
                                             respect to principal or interest payments.
                Ca.......................... Speculative in a high degree; could be in default or have
                                             other marked shortcomings.
                C........................... Lowest-rated; extremely poor prospects of ever attaining
                                             investment standing.
</TABLE>

          Unrated securities will be treated as noninvestment grade securities
          unless a portfolio manager determines that such securities are the
          equivalent of investment grade securities. Securities that have
          received ratings from more than one agency are considered investment
          grade if at least one agency has rated the security investment grade.

                                            Explanation of rating categories  33
<PAGE>

SECURITIES HOLDINGS BY RATING CATEGORY

          During the fiscal period ended December 31, 1999, the percentage of
          securities holdings for Flexible Income Portfolio by rating category
          based upon a weighted monthly average was:

<TABLE>
<CAPTION>
                FLEXIBLE INCOME PORTFOLIO
                ----------------------------------------------------------------------------------------
                <S>                                                                       <C>
                    BONDS-S&P RATING:
                 AAA                                                                        5%
                 AA                                                                         6%
                 A                                                                         10%
                 BBB                                                                       23%
                 BB                                                                        12%
                 B                                                                         19%
                 CCC                                                                        2%
                 CC                                                                         0%
                 C                                                                          0%
                 Not Rated                                                                  6%
                 Preferred Stock                                                            2%
                 Cash and Options                                                          15%
                 TOTAL                                                                    100%
                ----------------------------------------------------------------------------------------
</TABLE>

          No other Portfolio described in this Prospectus held 5% or more of its
          assets in bonds rated below investment grade for the fiscal period
          ended December 31, 1999.

 34 Janus Aspen Series
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolios.

The Statement of Additional Information provides detailed
information about the Portfolios and is incorporated into this
Prospectus by reference. You may review the Portfolios' Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>


                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Growth Portfolio
                              Aggressive Growth Portfolio
                              International Growth Portfolio
                              Worldwide Growth Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                This prospectus describes four mutual funds (the "Portfolios")
                with a variety of investment objectives. Each Portfolio of Janus
                Aspen Series currently offers two or three classes of shares.
                The Service Shares, (the "Shares"), are offered by this
                prospectus in connection with investment in and payments under
                variable annuity contracts and variable life insurance contracts
                (collectively, "variable insurance contracts"), as well as
                certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. Certain Portfolios may not
                be available in connection with a particular contract and
                certain contracts may limit allocations among the Portfolios.
                See the accompanying contract prospectus for information
                regarding contract fees and expenses and any restrictions on
                purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolios.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Equity Portfolios........................................    2
                   Fees and expenses........................................    6
                INVESTMENT OBJECTIVES, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Equity Portfolios........................................    7
                   General portfolio policies...............................    9
                   Risks....................................................   11
                MANAGEMENT OF THE PORTFOLIOS
                   Investment adviser.......................................   13
                   Management expenses and expense limits...................   13
                   Investment personnel.....................................   14
                OTHER INFORMATION...........................................   16
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   18
                   Taxes....................................................   18
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   19
                   Purchases................................................   19
                   Redemptions..............................................   19
                   Frequent trading.........................................   20
                   Shareholder communications...............................   20
                FINANCIAL HIGHLIGHTS........................................   21
                GLOSSARY
                   Glossary of investment terms.............................   22

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

EQUITY PORTFOLIOS

          The Equity Portfolios are designed for long-term investors who seek
          growth of capital and who can tolerate the greater risks associated
          with common stock investments.

1. WHAT ARE THE INVESTMENT OBJECTIVES OF THE EQUITY PORTFOLIOS?

- --------------------------------------------------------------------------------

          DOMESTIC EQUITY PORTFOLIOS

          - GROWTH PORTFOLIO seeks long-term growth of capital in a manner
            consistent with the preservation of capital.

          - AGGRESSIVE GROWTH PORTFOLIO seeks long-term growth of capital.

          GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          - INTERNATIONAL GROWTH PORTFOLIO seeks long-term growth of capital.

          - WORLDWIDE GROWTH PORTFOLIO seeks long-term growth of capital in a
            manner consistent with the preservation of capital.

          The Portfolios' Trustees may change these objectives without a
          shareholder vote and the Portfolios will notify you of any changes
          that are material. If there is a material change to a Portfolio's
          objective or policies, you should consider whether that Portfolio
          remains an appropriate investment for you. There is no guarantee that
          a Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF THE EQUITY PORTFOLIOS?

          The portfolio managers apply a "bottom up" approach in choosing
          investments. In other words, they look for companies with earnings
          growth potential one at a time. If a portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of a Portfolio's assets may be in cash or similar investments.

          GROWTH PORTFOLIO invests primarily in common stocks selected for their
          growth potential. Although the Portfolio can invest in companies of
          any size, it generally invests in larger, more established companies.

          AGGRESSIVE GROWTH PORTFOLIO invests primarily in common stocks
          selected for their growth potential, and normally invests at least 50%
          of its equity assets in medium-sized companies.

          INTERNATIONAL GROWTH PORTFOLIO normally invests at least 65% of its
          total assets in securities of issuers from at least five different
          countries, excluding the United States. Although the Portfolio intends
          to invest substantially all of its assets in issuers located outside
          the United States, it may invest in U.S. issuers and it may at times
          invest all of its assets in fewer than five countries, or even a
          single country.

          WORLDWIDE GROWTH PORTFOLIO invests primarily in common stocks of
          companies of any size throughout the world. The Portfolio normally
          invests in issuers from at least five different countries, including
          the United States. The Portfolio may at times invest in fewer than
          five countries or even a single country.

 2 Janus Aspen Series
<PAGE>

3. WHAT ARE THE MAIN RISKS OF INVESTING IN THE EQUITY PORTFOLIOS?

          The biggest risk of investing in these Portfolios is that their
          returns may vary, and you could lose money. If you are considering
          investing in any of the Equity Portfolios, remember that they are each
          designed for long-term investors who can accept the risks of investing
          in a portfolio with significant common stock holdings. Common stocks
          tend to be more volatile than other investment choices.

          The value of a Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of a
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of a Portfolio's holdings decreases, that
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in a Portfolio you would get back less money.

          INTERNATIONAL GROWTH PORTFOLIO AND WORLDWIDE GROWTH PORTFOLIO may have
          significant exposure to foreign markets. As a result, their returns
          and NAV may be affected to a large degree by fluctuations in currency
          exchange rates or political or economic conditions in a particular
          country.

          AGGRESSIVE GROWTH PORTFOLIO is nondiversified. In other words, it may
          hold larger positions in a smaller number of securities than a
          diversified fund. As a result, a single security's increase or
          decrease in value may have a greater impact on the Portfolio's NAV and
          total return.

          An investment in these Portfolios is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in the Equity Portfolios by showing how each of the Equity
          Portfolios' performance has varied over time. The Portfolios' Service
          Shares commenced operations on December 31, 1999. The returns shown
          for the Service Shares of these Portfolios reflect the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses (ignoring any fee and expense
          limitations). The bar charts depict the change in performance from
          year-to-year during the period indicated but do not include charges
          and expenses attributable to any insurance product which would lower
          the performance illustrated. The Portfolios do not impose any sales or
          other charges that would affect total return computations. Total
          return figures include the effect of each Portfolio's expenses. The
          tables compare the average annual returns for the Service Shares of
          each Portfolio for the periods indicated to a broad-based securities
          market index.

                                                          Risk return summary  3
<PAGE>

           GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                             2.71%   29.96%   18.14%   22.49%   35.59%    43.01%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1998  27.71%  Worst Quarter  3rd-1998 (10.95%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Growth Portfolio                                          43.01%    29.53%         23.86%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                                                                      --------------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

           AGGRESSIVE GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                            16.33%   27.38%    7.72%   12.53%   34.19%   123.16%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1999  58.17%  Worst Quarter  3rd-1998 (15.00%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                         1 year     5 years       (9/13/93)
                <S>                                                      <C>        <C>        <C>
                Aggressive Growth Portfolio                              123.16%    35.83%         33.98%
                S&P MidCap 400 Index*                                     14.72%    23.05%         18.08%
                                                                     ---------------------------------------------
</TABLE>

           * The S&P MidCap 400 Index is an unmanaged group of 400 domestic
             stocks chosen for their market size, liquidity and industry group
             representation.

 4 Janus Aspen Series
<PAGE>

           INTERNATIONAL GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                                     23.15%   34.71%   18.36%   16.88%    79.52%
                                      1995     1996     1997     1998      1999

           Best Quarter  4th-1999  56.24%  Worst Quarter  3rd-1998 (17.76%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (5/2/94)
                <S>                                                       <C>       <C>        <C>
                International Growth Portfolio                            79.52%    33.17%         28.19%
                Morgan Stanley Capital International EAFE(R) Index*       26.96%    12.83%         11.22%
                                                                      ----------------------------------------
</TABLE>

           * The Morgan Stanley Capital International EAFE(R) Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 20 Developed Market countries in Europe,
             Australasia and the Far East.

           WORLDWIDE GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                             1.53%   27.29%   28.80%   21.91%   28.71%    63.49%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1999  41.62%  Worst Quarter  3rd-1998 (17.00%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Worldwide Growth Portfolio                                63.49%    33.28%         29.35%
                Morgan Stanley Capital International World Index*         24.93%    19.76%         16.41%
                                                                      --------------------------------------------
</TABLE>

           * The Morgan Stanley Capital International World Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 21 Developed Market countries in North
             America, Europe and the Asia/Pacific Region.

          The Equity Portfolios' past performance does not necessarily indicate
          how they will perform in the future.

                                                          Risk return summary  5
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolios. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of a Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolios in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. The information shown is based upon estimated gross
          expenses (without the effect of expense offset arrangements) the
          Shares expect to incur in their initial fiscal year. OWNERS OF
          VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE SHARES SHOULD REFER TO
          THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR A DESCRIPTION OF FEES
          AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT REFLECT DEDUCTIONS AT
          THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR ANY CHARGES THAT MAY
          BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                                    Distribution                       Total Annual Fund
                                                   Management          (12b-1)            Other            Operating
                                                       Fee             Fees(1)          Expenses          Expenses(2)
    <S>                                            <C>              <C>                 <C>            <C>
    Growth Portfolio                                  0.65%             0.25%             0.02%              0.92%
    Aggressive Growth Portfolio                       0.65%             0.25%             0.02%              0.92%
    International Growth Portfolio                    0.65%             0.25%             0.11%              1.01%
    Worldwide Growth Portfolio                        0.65%             0.25%             0.05%              0.95%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of each Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolios with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in each of the Portfolios for
   the time periods indicated then redeem all of your shares at the end of
   those periods. The example also assumes that your investment has a 5%
   return each year, and that the Portfolios' operating expenses remain the
   same. Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Growth Portfolio                                               $ 94      $  293
    Aggressive Growth Portfolio                                    $ 94      $  293
    International Growth Portfolio                                 $103      $  322
    Worldwide Growth Portfolio                                     $ 97      $  303
</TABLE>

 6 Janus Aspen Series
<PAGE>
                                     Investment objectives, principal investment
                                                strategies and risks

          Each of the Portfolios has a similar investment objective and similar
          principal investment strategies to a Janus retail fund:

<TABLE>
                  <S>                                         <C>
                  Growth Portfolio                                       Janus Fund
                  Aggressive Growth Portfolio                 Janus Enterprise Fund
                  International Growth Portfolio                Janus Overseas Fund
                  Worldwide Growth Portfolio                   Janus Worldwide Fund
</TABLE>

          Although it is anticipated that each Portfolio and its corresponding
          retail fund will hold similar securities, differences in asset size,
          cash flow needs and other factors may result in differences in
          investment performance. The expenses of each Portfolio and its
          corresponding retail fund are expected to differ. The variable
          contract owner will also bear various insurance related costs at the
          insurance company level. You should review the accompanying separate
          account prospectus for a summary of fees and expenses.

EQUITY PORTFOLIOS

          This section takes a closer look at the investment objectives of each
          of the Equity Portfolios, their principal investment strategies and
          certain risks of investing in the Equity Portfolios. Strategies and
          policies that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 11-12 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

INVESTMENT OBJECTIVES AND PRINCIPAL INVESTMENT STRATEGIES

DOMESTIC EQUITY PORTFOLIOS

          GROWTH PORTFOLIO
          Growth Portfolio seeks long-term growth of capital in a manner
          consistent with the preservation of capital. It pursues its objective
          by investing primarily in common stocks selected for their growth
          potential. Although the Portfolio can invest in companies of any size,
          it generally invests in larger, more established companies.

          AGGRESSIVE GROWTH PORTFOLIO
          Aggressive Growth Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential, and normally invests at least 50% of its
          equity assets in medium-sized companies. Medium-sized companies are
          those whose market capitalization falls within the range of companies
          in the S&P MidCap 400 Index. Market capitalization is a commonly used
          measure of the size and value of a company. The market capitalizations
          within the Index will vary, but as of December 31, 1999, they ranged
          from approximately $170 million to $37 billion.

             Investment objectives, principal investment strategies and risks  7
<PAGE>

GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          INTERNATIONAL GROWTH PORTFOLIO
          International Growth Portfolio seeks long-term growth of capital.
          Normally, the Portfolio pursues its objective by investing at least
          65% of its total assets in securities of issuers from at least five
          different countries, excluding the United States. Although the
          Portfolio intends to invest substantially all of its assets in issuers
          located outside the United States, it may at times invest in U.S.
          issuers and it may at times invest all of its assets in fewer than
          five countries or even a single country.

          WORLDWIDE GROWTH PORTFOLIO
          Worldwide Growth Portfolio seeks long-term growth of capital in a
          manner consistent with the preservation of capital. It pursues its
          objective by investing primarily in common stocks of companies of any
          size throughout the world. The Portfolio normally invests in issuers
          from at least five different countries, including the United States.
          The Portfolio may at times invest in fewer than five countries or even
          a single country.

The following questions and answers are designed to help you better understand
the Equity Portfolios' principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          Each of the Portfolios may invest substantially all of its assets in
          common stocks if its portfolio manager believes that common stocks
          will appreciate in value. The portfolio managers generally take a
          "bottom up" approach to selecting companies. In other words, they seek
          to identify individual companies with earnings growth potential that
          may not be recognized by the market at large. They make this
          assessment by looking at companies one at a time, regardless of size,
          country of organization, place of principal business activity, or
          other similar selection criteria. Realization of income is not a
          significant consideration when choosing investments for the
          Portfolios. Income realized on the Portfolios' investments may be
          incidental to their objectives.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio managers seek companies that meet their
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolios may invest and
          the Portfolios may at times have significant foreign exposure.

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. As noted previously, market capitalization is
          an important investment criteria for Aggressive Growth Portfolio.
          Although the other Equity Portfolios offered by this Prospectus do not
          emphasize companies of any particular size, Portfolios with a larger
          asset base are more likely to invest in larger, more established
          issuers.

 8 Janus Aspen Series

<PAGE>

GENERAL PORTFOLIO POLICIES

          Unless otherwise stated, each of the following policies applies to all
          of the Portfolios. The percentage limitations included in these
          policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if a Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When a portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he or she is otherwise
          unable to locate attractive investment opportunities, the Portfolios'
          cash or similar investments may increase. In other words, the
          Portfolios do not always stay fully invested in stocks and bonds. Cash
          or similar investments generally are a residual - they represent the
          assets that remain after a portfolio manager has committed available
          assets to desirable investment opportunities. However, a portfolio
          manager may also temporarily increase a Portfolio's cash position to
          protect its assets or maintain liquidity. Partly because the portfolio
          managers act independently of each other, the cash positions of the
          Portfolios may vary significantly.

          When a Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          The Equity Portfolios invest primarily in domestic and foreign equity
          securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Equity Portfolios also invest in domestic and foreign equity
          securities with varying degrees of emphasis on income. The Portfolios
          may also invest to a lesser degree in other types of securities. These
          securities (which are described in the Glossary) may include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of each Portfolio's
            assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          Each Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolios' Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolios may invest without limit in foreign equity and debt
          securities. The Portfolios may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United

             Investment objectives, principal investment strategies and risks  9
<PAGE>

          States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

          SPECIAL SITUATIONS
          Each Portfolio may invest in special situations. A special situation
          arises when, in the opinion of a Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. A Portfolio's performance could
          suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolios generally intend to purchase securities for long-term
          investment although, to a limited extent, a Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. A Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in a Portfolio's holdings whenever its
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in a Portfolio's
          performance.

 10 Janus Aspen Series
<PAGE>

RISKS

          Because the Portfolios may invest substantially all of their assets in
          common stocks, the main risk is the risk that the value of the stocks
          they hold might decrease in response to the activities of an
          individual company or in response to general market and/or economic
          conditions. If this occurs, a Portfolio's share price may also
          decrease. A Portfolio's performance may also be affected by risks
          specific to certain types of investments, such as foreign securities,
          derivative investments, non-investment grade debt securities, initial
          public offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in the Portfolios.

1. THE PORTFOLIOS MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF AGGRESSIVE GROWTH PORTFOLIO AFFECT ITS
   RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of the Portfolio.

3. HOW COULD THE PORTFOLIOS' INVESTMENTS IN FOREIGN SECURITIES AFFECT THEIR
   PERFORMANCE?

          The Portfolios may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolios' performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as a Portfolio holds a foreign security, its
            value will be affected by the value of the local currency relative
            to the U.S. dollar. When a Portfolio sells a foreign denominated
            security, its value may be worth less in U.S. dollars even if the
            security increases in value in its home country. U.S. dollar
            denominated securities of foreign issuers may also be affected by
            currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may

            Investment objectives, principal investment strategies and risks  11
<PAGE>

            take over the assets or operations of a company or that the
            government may impose taxes or limits on the removal of a
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

4. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

5. HOW DO THE PORTFOLIOS TRY TO REDUCE RISK?

          The Portfolios may use futures, options, swaps and other derivative
          instruments to "hedge" or protect their portfolios from adverse
          movements in securities prices and interest rates. The Portfolios may
          also use a variety of currency hedging techniques, including forward
          currency contracts, to manage exchange rate risk. The portfolio
          managers believe the use of these instruments will benefit the
          Portfolios. However, a Portfolio's performance could be worse than if
          the Portfolio had not used such instruments if a portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 12 Janus Aspen Series
<PAGE>
                                                    Management of the portfolios

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to each of the Portfolios and is responsible
          for the day-to-day management of the investment portfolios and other
          business affairs of the Portfolios.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning each Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolios, and may be reimbursed by the Portfolios for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolios and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolios' Shares
          may perform certain administrative services relating to the Portfolios
          and Janus Capital or the Portfolios may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          Each Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with each Portfolio
          spells out the management fee and other expenses that the Portfolios
          must pay. Each of the Portfolios is subject to the following
          management fee schedule (expressed as an annual rate). In addition,
          the Shares of each Portfolio incur expenses not assumed by Janus
          Capital, including the distribution fee, transfer agent and custodian
          fees and expenses, legal and auditing fees, printing and mailing costs
          of sending reports and other information to existing shareholders, and
          independent Trustees' fees and expenses.

<TABLE>
<CAPTION>
                                                                     Average Daily
                                                                      Net Assets          Annual Rate
     Fee Schedule                                                     of Portfolio       Percentage (%)
- -----------------------------------------------------------------------------------------------------------
<S>                                                                 <C>                  <C>
     Growth Portfolio                                               All Asset Levels         0.65
     Aggressive Growth Portfolio
     International Growth Portfolio
     Worldwide Growth Portfolio
- -----------------------------------------------------------------------------------------------------------
</TABLE>

          For the fiscal year ended December 31, 1999, each Portfolio paid Janus
          Capital the following management fees based upon each Portfolio's
          average net assets: 0.67% for Growth Portfolio, 0.68% for Aggressive
          Growth Portfolio, 0.73% for International Growth Portfolio and 0.66%
          for Worldwide Growth Portfolio. These rates were based on a higher fee
          rate that was previously in effect for these Portfolios.

                                                Management of the portfolios  13
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGERS

LAURENCE J. CHANG
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio which he has
            co-managed since May 1998 and December 1999, respectively. He has
            also co-managed Janus Overseas Fund and Janus Worldwide Fund
            since April 1998 and September 1999, respectively. He served as
            assistant portfolio manager for these funds since 1996. Mr. Chang
            joined Janus Capital in 1993 as a research analyst. He received
            an undergraduate degree with honors in Religion with a
            concentration in Philosophy from Dartmouth College and a Masters
            Degree in Political Science from Stanford University. He has
            earned the right to use the Chartered Financial Analyst
            designation.

JAMES P. GOFF
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Aggressive
            Growth Portfolio, which he has managed since inception. Mr. Goff
            joined Janus Capital in 1988 and has managed Janus Enterprise
            Fund since its inception. Mr. Goff co-managed or managed Janus
            Venture Fund from December 1993 to February 1997. He holds a
            Bachelor of Arts in Economics from Yale University and he has
            earned the right to use the Chartered Financial Analyst
            designation.

HELEN YOUNG HAYES
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio, which she has
            managed or co-managed since inception. Ms. Hayes joined Janus
            Capital in 1987 and has managed or co-managed Janus Worldwide
            Fund and Janus Overseas Fund since their inceptions. She holds a
            Bachelor of Arts in Economics from Yale University and she has
            earned the right to use the Chartered Financial Analyst
            designation.

BLAINE P. ROLLINS
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Growth
            Portfolio as of January 2000. He previously managed Balanced
            Portfolio from May 1996 to December 1999 and Equity Income
            Portfolio from its inception to December 1999. Mr. Rollins joined
            Janus Capital in 1990 and has managed Janus Fund since January
            2000, Janus Balanced Fund from January 1996 until December 1999
            and Janus Equity Income Fund from inception until December 1999.
            He was an assistant portfolio manager of Janus Fund from January
            1994 until December 1999. He gained experience as a fixed-income
            trader and equity research analyst prior to managing Balanced
            Portfolio. He holds a Bachelor of Science in Finance from the
            University of Colorado and he has earned the right to use the
            Chartered Financial Analyst designation.

 14 Janus Aspen Series
<PAGE>

ASSISTANT PORTFOLIO MANAGERS

MATTHEW A. ANKRUM
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            He is also assistant portfolio manager of Janus Enterprise Fund.
            Mr. Ankrum joined Janus Capital as an intern in June 1996, and
            became an equity research analyst in August 1997. Prior to
            joining Janus, Mr. Ankrum worked as a corporate finance analyst
            at William Blair and Company from 1993 through 1995. He was also
            a fixed-income research analyst at Conseco Capital Management.
            Mr. Ankrum has an undergraduate degree in Business Administration
            from the University of Wisconsin and a Master of Business
            Administration from the University of Chicago. Mr. Ankrum has
            earned the right to use the Chartered Financial Analyst
            designation.

DAVID C. DECKER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. He is also
            an assistant portfolio manager of Janus Fund. He is Executive
            Vice President and portfolio manager of Strategic Value
            Portfolio, Janus Strategic Value Fund and Janus Special
            Situations Fund, each of which he has managed since its
            inception. He obtained a Masters of Business Administration in
            Finance from the Fuqua School of Business at Duke University and
            a Bachelor of Arts in Economics and Political Science from Tufts
            University. Mr. Decker has earned the right to use the Chartered
            Financial Analyst designation.

RON SACHS
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            Mr. Sachs joined Janus Capital in 1996 as a research analyst.
            Prior to coming to Janus, he worked as a consultant for Bain &
            Company and as an attorney for Willkie, Farr & Gallagher. Mr.
            Sachs graduated from Princeton cum laude with an undergraduate
            degree in economics. He obtained his law degree from the
            University of Michigan. Mr. Sachs has earned the right to use the
            Chartered Financial Analyst designation.

JOHN H. SCHREIBER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. Mr.
            Schreiber joined Janus Capital in 1997 as an equity research
            analyst. Prior to coming to Janus he was an equity analyst with
            Fidelity Investments. Mr. Schreiber holds a Bachelor of Science
            degree in mechanical engineering from the University of
            Washington and an MBA from Harvard University.

                                                Management of the portfolios  15
<PAGE>
Other information

          CLASSES OF SHARES

          Each Portfolio currently offers two or three classes of shares, one of
          which, the Service Shares, are offered pursuant to this prospectus.
          The Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of each
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of certain Portfolios
          are offered only to qualified plans using plan service providers that
          are compensated for providing distribution and/or record keeping and
          other administrative services provided to plan participants. Because
          the expenses of each class may differ, the performance of each class
          is expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, each Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of a Portfolio. Under the terms
          of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolios do not currently anticipate any disadvantages to owners
          of variable insurance contracts because each Portfolio offers its
          shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in one or more Portfolios or substitute
          Shares of another Portfolio. If this occurs, a Portfolio may be forced
          to sell its securities at disadvantageous prices. In addition, the
          Trustees may refuse to sell Shares of any Portfolio to any separate
          account or qualified plan or may suspend or terminate the offering of
          a Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of that Portfolio's
          shareholders. It is possible that a qualified plan investing in the
          Portfolios could lose its qualified plan status under the Internal
          Revenue Code, which could have adverse tax consequences on insurance
          company separate accounts investing in the Shares. Janus Capital
          intends to monitor such qualified plans and the Portfolios may
          discontinue sales to a qualified plan and require plan participants
          with existing investments in the Shares to redeem those investments if
          a plan loses (or in the opinion of Janus Capital is at risk of losing)
          its qualified plan status.

 16 Janus Aspen Series
<PAGE>

          DISTRIBUTION OF EACH PORTFOLIO

          Each Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

                                                           Other information  17
<PAGE>
Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolios, the Internal Revenue Code
          requires each Portfolio to distribute net income and any net gains
          realized on its investments annually. A Portfolio's income from
          dividends and interest and any net realized short-term gains are paid
          to shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of each Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of a Portfolio will automatically be
          reinvested into additional Shares of that Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of a Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of a Portfolio's Shares. The Share price of a Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Growth Portfolio declared a dividend in the amount of $0.25 per share.
          If the price of Growth Portfolio's Shares was $10.00 on December 30,
          the share price on December 31 would be $9.75, barring market
          fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolios may be purchased only through
          variable insurance contracts and qualified plans, it is anticipated
          that any income dividends or capital gains distributions made by the
          Shares of a Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIOS

          Dividends, interest and some gains received by the Portfolios on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolios may from year to year make the election
          permitted under Section 853 of the Internal Revenue Code to pass
          through such taxes to shareholders as a foreign tax credit. If such
          election is not made, any foreign taxes paid or accrued will represent
          an expense to the Portfolios which will reduce their investment
          income.

          The Portfolios do not expect to pay any federal income or excise taxes
          because they intend to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of each Portfolio
          are sold in connection with variable insurance contracts, each
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

 18 Janus Aspen Series
<PAGE>
                                                             Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIOS
          DIRECTLY. SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE
          INSURANCE CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING
          INSURANCE COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. CERTAIN
          PORTFOLIOS MAY NOT BE AVAILABLE IN CONNECTION WITH A PARTICULAR
          CONTRACT AND CERTAIN CONTRACTS MAY LIMIT ALLOCATIONS AMONG THE
          PORTFOLIOS. REFER TO THE PROSPECTUS FOR THE PARTICIPATING INSURANCE
          COMPANY'S SEPARATE ACCOUNT OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON
          PURCHASING OR SELLING OF VARIABLE INSURANCE CONTRACTS AND ON HOW TO
          SELECT SPECIFIC PORTFOLIOS AS INVESTMENT OPTIONS FOR A CONTRACT OR A
          QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by a Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolios are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent a Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolios do not price their shares, the NAV of a Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of each Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolios' behalf.

          The Portfolios do not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. Each Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of a Portfolio. Although there is no present intention
          to do so, the Portfolios may discontinue sales of their shares if
          management and the Trustees believe that continued sales may adversely
          affect a Portfolio's ability to achieve its investment objective. If
          sales of a Portfolio's Shares are discontinued, it is expected that
          existing participants invested in that Portfolio would be permitted to
          continue to authorize investment in that Portfolio and to reinvest any
          dividends or capital gains distributions, absent highly unusual
          circumstances. The Portfolios may discontinue sales to a qualified
          plan and require plan participants with existing investments in the
          Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

                                                         Shareholder's guide  19
<PAGE>

          Shares of any Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption proceeds will normally be wired the business day following
          receipt of the redemption order, but in no event later than seven days
          after receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage a Portfolio's investments. The
          Portfolios do not permit frequent trading or market timing. When
          market timing occurs, a Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm a Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash a Portfolio will have to invest. When in
          Janus Capital's opinion such activity would have a disruptive effect
          on portfolio management, a Portfolio reserves the right to refuse
          purchase orders and exchanges into a Portfolio by any person, group or
          commonly controlled account. A Portfolio may notify a market timer of
          rejection of a purchase or exchange order after the day the order is
          placed. If a Portfolio allows a market timer to trade Portfolio
          shares, it may require the market timer to enter into a written
          agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolios that they have
          authorized for investment. Each report will show the investments owned
          by each Portfolio and the market values thereof, as well as other
          information about the Portfolios and their operations. The Trust's
          fiscal year ends December 31.

 20 Janus Aspen Series
<PAGE>
                                                            Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

                                                        Financial highlights  21
<PAGE>
Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolios may
          invest. The Portfolios may invest in these instruments to the extent
          permitted by their investment objectives and policies. The Portfolios
          are not limited by this discussion and may invest in any other types
          of instruments not precluded by the policies discussed elsewhere in
          this Prospectus. Please refer to the SAI for a more detailed
          discussion of certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolios may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, a portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

 22 Janus Aspen Series
<PAGE>

          Portfolios must pay if these investments are profitable, the
          Portfolios may make various elections permitted by the tax laws. These
          elections could require that the Portfolios recognize taxable income,
          which in turn must be distributed, before the securities are sold and
          before cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by a
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, a Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by a
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by a Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

                                                Glossary of investment terms  23
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolios do
          not earn interest on such securities until settlement and bear the
          risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolios may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. They may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolios may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolios may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          A Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

 24 Janus Aspen Series
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolios may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

                                                Glossary of investment terms  25
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolios.

The Statement of Additional Information provides detailed
information about the Portfolios and is incorporated into this
Prospectus by reference. You may review the Portfolios' Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>


                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Aggressive Growth Portfolio
                              Balanced Portfolio
                              Growth and Income Portfolio
                              International Growth Portfolio
                              Worldwide Growth Portfolio
                              Global Life Sciences Portfolio
                              Global Technology Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                This prospectus describes seven mutual funds (the "Portfolios")
                with a variety of investment objectives, including growth of
                capital, current income and a combination of growth and income.
                Each Portfolio of Janus Aspen Series currently offers two or
                three classes of shares. The Service Shares, (the "Shares"), are
                offered by this prospectus in connection with investment in and
                payments under variable annuity contracts and variable life
                insurance contracts (collectively, "variable insurance
                contracts"), as well as certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. Certain Portfolios may not
                be available in connection with a particular contract and
                certain contracts may limit allocations among the Portfolios.
                See the accompanying contract prospectus for information
                regarding contract fees and expenses and any restrictions on
                purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolios.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Equity Portfolios........................................    2
                   Fees and expenses........................................    8
                INVESTMENT OBJECTIVES, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Equity Portfolios........................................    9
                   General portfolio policies...............................   13
                   Risks....................................................   15
                MANAGEMENT OF THE PORTFOLIOS
                   Investment adviser.......................................   18
                   Management expenses and expense limits...................   18
                   Investment personnel.....................................   19
                OTHER INFORMATION...........................................   22
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   24
                   Taxes....................................................   24
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   25
                   Purchases................................................   25
                   Redemptions..............................................   25
                   Frequent trading.........................................   26
                   Shareholder communications...............................   26
                FINANCIAL HIGHLIGHTS........................................   27
                GLOSSARY
                   Glossary of investment terms.............................   28

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

EQUITY PORTFOLIOS

          The Equity Portfolios are designed for long-term investors who seek
          growth of capital and who can tolerate the greater risks associated
          with common stock investments.

1. WHAT ARE THE INVESTMENT OBJECTIVES OF THE EQUITY PORTFOLIOS?

- --------------------------------------------------------------------------------

          DOMESTIC EQUITY PORTFOLIOS

          - AGGRESSIVE GROWTH PORTFOLIO seeks long-term growth of capital.

          - BALANCED PORTFOLIO seeks long-term capital growth, consistent
            with preservation of capital and balanced by current income.

          - GROWTH AND INCOME PORTFOLIO seeks long-term capital growth and
            current income.

          GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          - INTERNATIONAL GROWTH PORTFOLIO, GLOBAL LIFE SCIENCES PORTFOLIO
            AND GLOBAL TECHNOLOGY PORTFOLIO seek long-term growth of capital.

          - WORLDWIDE GROWTH PORTFOLIO seeks long-term growth of capital in a
            manner consistent with the preservation of capital.

          The Portfolios' Trustees may change these objectives without a
          shareholder vote and the Portfolios will notify you of any changes
          that are material. If there is a material change to a Portfolio's
          objective or policies, you should consider whether that Portfolio
          remains an appropriate investment for you. There is no guarantee that
          a Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF THE EQUITY PORTFOLIOS?

          The portfolio managers apply a "bottom up" approach in choosing
          investments. In other words, they look for companies with earnings
          growth potential one at a time. If a portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of a Portfolio's assets may be in cash or similar investments.

          AGGRESSIVE GROWTH PORTFOLIO invests primarily in common stocks
          selected for their growth potential, and normally invests at least 50%
          of its equity assets in medium-sized companies.

          BALANCED PORTFOLIO normally invests 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. The
          Portfolio will normally invest at least 25% of its assets in
          fixed-income securities.

          GROWTH AND INCOME PORTFOLIO normally emphasizes investments in common
          stocks. It will normally invest up to 75% of its assets in equity
          securities selected primarily for their growth potential, and at least
          25% of its assets in securities the portfolio manager believes have
          income potential. Equity securities may make up part of this income
          component if they currently pay dividends or the portfolio manager
          believes they have potential for increasing or commencing dividend
          payments.

          INTERNATIONAL GROWTH PORTFOLIO normally invests at least 65% of its
          total assets in securities of issuers from at least five different
          countries, excluding the United States. Although the Portfolio intends
          to invest

 2 Janus Aspen Series
<PAGE>

          substantially all of its assets in issuers located outside the United
          States, it may invest in U.S. issuers and it may at times invest all
          of its assets in fewer than five countries, or even a single country.

          WORLDWIDE GROWTH PORTFOLIO invests primarily in common stocks of
          companies of any size throughout the world. The Portfolio normally
          invests in issuers from at least five different countries, including
          the United States. The Portfolio may at times invest in fewer than
          five countries or even a single country.

          GLOBAL LIFE SCIENCES PORTFOLIO invests primarily in equity securities
          of U.S. and foreign companies selected for their growth potential.
          Normally, it invests at least 65% of its total assets in securities of
          companies that the portfolio manager believes have a life science
          orientation. Generally speaking, the "life sciences" relate to
          maintaining or improving quality of life. So, for example, companies
          with a "life science orientation" include companies engaged in
          research, development, production or distribution of products or
          services related to health and personal care, medicine or
          pharmaceuticals. As a fundamental policy, the Portfolio normally
          invests at least 25% of its total assets, in the aggregate, in the
          following industry groups: healthcare; pharmaceuticals; agriculture;
          cosmetics/personal care; and biotechnology.

          GLOBAL TECHNOLOGY PORTFOLIO invests primarily in equity securities of
          U.S. and foreign companies selected for their growth potential. Under
          normal circumstances, it invests at least 65% of its total assets in
          securities of companies that the portfolio manager believes will
          benefit significantly from advances or improvements in technology.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN THE EQUITY PORTFOLIOS?

          The biggest risk of investing in these Portfolios is that their
          returns may vary, and you could lose money. If you are considering
          investing in any of the Equity Portfolios, remember that they are each
          designed for long-term investors who can accept the risks of investing
          in a portfolio with significant common stock holdings. Common stocks
          tend to be more volatile than other investment choices.

          The value of a Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of a
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of a Portfolio's holdings decreases, that
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in a Portfolio you would get back less money.

          The income component of the BALANCED PORTFOLIO AND GROWTH AND INCOME
          PORTFOLIO includes fixed-income securities. A fundamental risk to the
          income component is that the value of these securities will fall if
          interest rates rise. Generally, the value of a fixed-income portfolio
          will decrease when interest rates rise, which means the Portfolio's
          NAV may likewise decrease. Another fundamental risk associated with
          fixed-income securities is credit risk, which is the risk that an
          issuer of a bond will be unable to make principal and interest
          payments when due.

          GLOBAL LIFE SCIENCES PORTFOLIO concentrates its investments in related
          industry groups. Because of this, companies in its portfolio may share
          common characteristics and react similarly to market developments. For
          example, many companies with a life science orientation are highly
          regulated and may be dependent upon certain types of technology. As a
          result, changes in government funding or subsidies, new or anticipated
          legislative changes, or technological advances could affect the value
          of such companies and, therefore, the Portfolio's NAV. The Portfolio's
          returns may be more volatile than those of a less concentrated
          portfolio.

          Although GLOBAL TECHNOLOGY PORTFOLIO does not concentrate its
          investments in specific industries, it may invest in companies related
          in such a way that they react similarly to certain market pressures.
          For example, competition among technology companies may result in
          increasingly aggressive pricing of their

                                                          Risk return summary  3
<PAGE>

          products and services, which may affect the profitability of companies
          in the portfolio. In addition, because of the rapid pace of
          technological development, products or services developed by companies
          in the Portfolio's portfolio may become rapidly obsolete or have
          relatively short product cycles. As a result, the Portfolio's returns
          may be considerably more volatile than the returns of a fund that does
          not invest in similarly related companies.

          INTERNATIONAL GROWTH PORTFOLIO, WORLDWIDE GROWTH PORTFOLIO, GLOBAL
          LIFE SCIENCES PORTFOLIO AND GLOBAL TECHNOLOGY PORTFOLIO may have
          significant exposure to foreign markets. As a result, their returns
          and NAV may be affected to a large degree by fluctuations in currency
          exchange rates or political or economic conditions in a particular
          country.

          AGGRESSIVE GROWTH PORTFOLIO, GLOBAL LIFE SCIENCES PORTFOLIO AND GLOBAL
          TECHNOLOGY PORTFOLIO are nondiversified. In other words, they may hold
          larger positions in a smaller number of securities than a diversified
          fund. As a result, a single security's increase or decrease in value
          may have a greater impact on a Portfolio's NAV and total return.

          An investment in these Portfolios is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in the Equity Portfolios by showing how each of the Equity
          Portfolios' performance has varied over time. The Portfolios' Service
          Shares commenced operations on December 31, 1999. The returns shown
          for the Service Shares of these Portfolios reflect the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses (ignoring any fee and expense
          limitations). The bar charts depict the change in performance from
          year-to-year during the period indicated but do not include charges
          and expenses attributable to any insurance product which would lower
          the performance illustrated. The Portfolios do not impose any sales or
          other charges that would affect total return computations. Total
          return figures include the effect of each Portfolio's expenses. The
          tables compare the average annual returns for the Service Shares of
          each Portfolio for the periods indicated to a broad-based securities
          market index.

 4 Janus Aspen Series
<PAGE>

           AGGRESSIVE GROWTH PORTFOLIO

            Annual Returns for Periods Ended 12/31

                            16.33%   27.38%    7.72%   12.53%   34.19%   123.16%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1999  58.17%  Worst Quarter  3rd-1998 (15.00%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                         1 year     5 years       (9/13/93)
                <S>                                                  <C>            <C>        <C>
                Aggressive Growth Portfolio                              123.16%    35.83%         33.98%
                S&P MidCap 400 Index*                                     14.72%    23.05%         18.08%
                                                                     -----------------------------------------
</TABLE>

           * The S&P MidCap 400 Index is an unmanaged group of 400 domestic
             stocks chosen for their market size, liquidity and industry group
             representation.

           BALANCED PORTFOLIO

           Annual Returns for Periods Ended 12/31

                             0.84%   24.79%   16.18%   21.96%   34.03%    26.03%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1998  20.26%  Worst Quarter  3rd-1998 (5.02%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                   <C>           <C>        <C>
                Balanced Portfolio                                        26.03%    24.55%         20.51%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                Lehman Brothers Gov't/Corp Bond Index**                   (2.15%)    7.61%          5.40%
                                                                      ----------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

          ** Lehman Brothers Gov't/Corp Bond Index is composed of all bonds that
             are of investment grade with at least one year until maturity.

                                                          Risk return summary  5
<PAGE>

           GROWTH AND INCOME PORTFOLIO

           Annual Returns for Periods Ended 12/31

                                                                          73.09%
                                                                           1999

           Best Quarter  4th-1999  37.51%  Worst Quarter  3rd-1999 4.30%


                           Average annual total return for period ended 12/31/99
                           -----------------------------------------------------

<TABLE>
<CAPTION>
                                                                                           Since Inception
                                                                                 1 year       (5/1/98)
                <S>                                                          <C>           <C>
                Growth and Income Portfolio                                      73.09%        54.92%
                S&P 500 Index*                                                   21.03%        19.85%
                                                                             -----------------------------
</TABLE>

          * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
            a widely recognized, unmanaged index of common stock prices.

           INTERNATIONAL GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                                     23.15%   34.71%   18.36%   16.88%    79.52%
                                      1995     1996     1997     1998      1999

           Best Quarter  4th-1999  56.24%  Worst Quarter  3rd-1998 (17.76%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (5/2/94)
                <S>                                                   <C>           <C>        <C>
                International Growth Portfolio                            79.52%    33.17%         28.19%
                Morgan Stanley Capital International EAFE(R) Index*       26.96%    12.83%         11.22%
                                                                      ----------------------------------------
</TABLE>

           * The Morgan Stanley Capital International EAFE(R) Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 20 Developed Market countries in Europe,
             Australasia and the Far East.

 6 Janus Aspen Series
<PAGE>

           WORLDWIDE GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                             1.53%   27.29%   28.80%   21.91%   28.71%    63.49%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1999  41.62%  Worst Quarter  3rd-1998 (17.00%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                   <C>           <C>        <C>
                Worldwide Growth Portfolio                                63.49%    33.28%         29.35%
                Morgan Stanley Capital International World Index*         24.93%    19.76%         16.41%
                                                                      ----------------------------------------
</TABLE>

           * The Morgan Stanley Capital International World Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 21 Developed Market countries in North
             America, Europe and the Asia/Pacific Region.

          Since Global Life Sciences Portfolio and Global Technology Portfolio
          did not commence operations until January 15, 2000, there is no
          performance available as of the date of this prospectus.

          The Equity Portfolios' past performance does not necessarily indicate
          how they will perform in the future.

                                                          Risk return summary  7
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolios. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of a Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolios in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                               Distribution                        Total Annual Fund
                                             Management           (12b-1)           Other              Operating
                                                 Fee              Fees(1)         Expenses            Expenses(2)
    <S>                                      <C>               <C>                <C>              <C>
    Aggressive Growth Portfolio                0.65%              0.25%            0.02%                 0.92%
    Balanced Portfolio                         0.65%              0.25%            0.02%                 0.92%
    Growth and Income Portfolio                0.65%              0.25%            0.40%                 1.30%
    International Growth Portfolio             0.65%              0.25%            0.11%                 1.01%
    Worldwide Growth Portfolio                 0.65%              0.25%            0.05%                 0.95%
    Global Life Sciences Portfolio             0.65%              0.25%            0.19%                 1.09%
    Global Technology Portfolio                0.65%              0.25%            0.13%                 1.03%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of each Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolios with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in each of the Portfolios for
   the time periods indicated then redeem all of your shares at the end of
   those periods. The example also assumes that your investment has a 5%
   return each year, and that the Portfolios' operating expenses remain the
   same. Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Aggressive Growth Portfolio                                    $ 94      $  293
    Balanced Portfolio                                             $ 94      $  293
    Growth and Income Portfolio                                    $132      $  412
    International Growth Portfolio                                 $103      $  322
    Worldwide Growth Portfolio                                     $ 97      $  303
    Global Life Sciences Portfolio                                 $111      $  347
    Global Technology Portfolio                                    $105      $  328
</TABLE>

 8 Janus Aspen Series
<PAGE>
                                     Investment objectives, principal investment
                                                strategies and risks

          Each of the Portfolios has a similar investment objective and similar
          principal investment strategies to a Janus retail fund:

<TABLE>
                  <S>                                         <C>
                  Aggressive Growth Portfolio                           Janus Enterprise Fund
                  Balanced Portfolio                                      Janus Balanced Fund
                  Growth and Income Portfolio                    Janus Growth and Income Fund
                  International Growth Portfolio                          Janus Overseas Fund
                  Worldwide Growth Portfolio                             Janus Worldwide Fund
                  Global Life Sciences Portfolio              Janus Global Life Sciences Fund
                  Global Technology Portfolio                    Janus Global Technology Fund
</TABLE>

          Although it is anticipated that each Portfolio and its corresponding
          retail fund will hold similar securities, differences in asset size,
          cash flow needs and other factors may result in differences in
          investment performance. The expenses of each Portfolio and its
          corresponding retail fund are expected to differ. The variable
          contract owner will also bear various insurance related costs at the
          insurance company level. You should review the accompanying separate
          account prospectus for a summary of fees and expenses.

EQUITY PORTFOLIOS

          This section takes a closer look at the investment objectives of each
          of the Equity Portfolios, their principal investment strategies and
          certain risks of investing in the Equity Portfolios. Strategies and
          policies that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 15-17 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

INVESTMENT OBJECTIVES AND PRINCIPAL INVESTMENT STRATEGIES

DOMESTIC EQUITY PORTFOLIOS

          AGGRESSIVE GROWTH PORTFOLIO
          Aggressive Growth Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential, and normally invests at least 50% of its
          equity assets in medium-sized companies. Medium-sized companies are
          those whose market capitalization falls within the range of companies
          in the S&P MidCap 400 Index. Market capitalization is a commonly used
          measure of the size and value of a company. The market capitalizations
          within the Index will vary, but as of December 31, 1999, they ranged
          from approximately $170 million to $37 billion.

          BALANCED PORTFOLIO
          Balanced Portfolio seeks long-term capital growth, consistent with
          preservation of capital and balanced by current income. It pursues its
          objective by normally investing 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. This
          Portfolio normally invests at least 25% of its assets in fixed-income
          securities.

          GROWTH AND INCOME PORTFOLIO
          Growth and Income Portfolio seeks long-term capital growth and current
          income. It normally emphasizes investments in common stocks. It will
          normally invest up to 75% of its assets in equity securities selected

             Investment objectives, principal investment strategies and risks  9
<PAGE>

          primarily for their growth potential, and at least 25% of its assets
          in securities the portfolio manager believes have income potential.
          Because of this investment strategy, the Portfolio is not designed for
          investors who need consistent income.

GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          INTERNATIONAL GROWTH PORTFOLIO
          International Growth Portfolio seeks long-term growth of capital.
          Normally, the Portfolio pursues its objective by investing at least
          65% of its total assets in securities of issuers from at least five
          different countries, excluding the United States. Although the
          Portfolio intends to invest substantially all of its assets in issuers
          located outside the United States, it may at times invest in U.S.
          issuers and it may at times invest all of its assets in fewer than
          five countries or even a single country.

          WORLDWIDE GROWTH PORTFOLIO
          Worldwide Growth Portfolio seeks long-term growth of capital in a
          manner consistent with the preservation of capital. It pursues its
          objective by investing primarily in common stocks of companies of any
          size throughout the world. The Portfolio normally invests in issuers
          from at least five different countries, including the United States.
          The Portfolio may at times invest in fewer than five countries or even
          a single country.

          GLOBAL LIFE SCIENCES PORTFOLIO
          Global Life Sciences Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in equity securities of
          U.S. and foreign companies selected for their growth potential.
          Normally, it invests at least 65% of its total assets in securities of
          companies that the portfolio manager believes have a life science
          orientation. As a fundamental policy, the Portfolio normally invests
          at least 25% of its total assets, in the aggregate, in the following
          industry groups: health care; pharmaceuticals; agriculture;
          cosmetics/personal care; and biotechnology.

          GLOBAL TECHNOLOGY PORTFOLIO
          Global Technology Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in equity securities of
          U.S. and foreign companies selected for their growth potential.
          Normally, it invests at least 65% of its total assets in securities of
          companies that the portfolio manager believes will benefit
          significantly from advances or improvements in technology. These
          companies generally fall into two categories:

          a. Companies that the portfolio manager believes have or will develop
          products, processes or services that will provide significant
          technological advancements or improvements; and

          b. Companies that the portfolio manager believes rely extensively on
          technology in connection with their operations or services.

 10 Janus Aspen Series
<PAGE>

The following questions and answers are designed to help you better understand
the Equity Portfolios' principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          Each of the Portfolios may invest substantially all of its assets in
          common stocks if its portfolio manager believes that common stocks
          will appreciate in value. The portfolio managers generally take a
          "bottom up" approach to selecting companies. In other words, they seek
          to identify individual companies with earnings growth potential that
          may not be recognized by the market at large. They make this
          assessment by looking at companies one at a time, regardless of size,
          country of organization, place of principal business activity, or
          other similar selection criteria. Except for Balanced Portfolio and
          Growth and Income Portfolio, realization of income is not a
          significant consideration when choosing investments for the
          Portfolios. Income realized on the Portfolios' investments may be
          incidental to their objectives. In the case of Balanced Portfolio and
          Growth and Income Portfolio, a portfolio manager may consider
          dividend-paying characteristics to a greater degree in selecting
          common stock.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio managers seek companies that meet their
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolios may invest and
          the Portfolios may at times have significant foreign exposure.

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. As noted previously, market capitalization is
          an important investment criteria for Aggressive Growth Portfolio.
          Although the other Equity Portfolios offered by this Prospectus do not
          emphasize companies of any particular size, Portfolios with a larger
          asset base are more likely to invest in larger, more established
          issuers.

4. HOW DO BALANCED PORTFOLIO AND GROWTH AND INCOME PORTFOLIO DIFFER FROM EACH
   OTHER?

          Growth and Income Portfolio places a greater emphasis on aggressive
          growth stocks and may derive a greater portion of its income from
          dividend-paying common stocks. Because of these factors, its NAV can
          be expected to fluctuate more than Balanced Portfolio. Balanced
          Portfolio places a greater emphasis on the income component of its
          portfolio and invests to a greater degree in securities selected
          primarily for their income potential. As a result it is expected to be
          less volatile than Growth and Income Portfolio.

5. HOW ARE ASSETS ALLOCATED BETWEEN THE GROWTH AND INCOME COMPONENTS OF BALANCED
   PORTFOLIO'S AND GROWTH AND INCOME PORTFOLIO'S HOLDINGS?

          Balanced Portfolio and Growth and Income Portfolio shift assets
          between the growth and income components of their holdings based on
          the portfolio managers' analysis of relevant market, financial and
          economic conditions. If a portfolio manager believes that growth
          securities will provide better returns than the yields then available
          or expected on income-producing securities, that Portfolio will place
          a greater emphasis on the growth component.

            Investment objectives, principal investment strategies and risks  11
<PAGE>

6. WHAT TYPES OF SECURITIES MAKE UP THE GROWTH COMPONENT OF THE BALANCED
   PORTFOLIO AND GROWTH AND INCOME PORTFOLIO?

          The growth component of these Portfolios is expected to consist
          primarily of common stocks, but may also include warrants, preferred
          stocks or convertible securities selected primarily for their growth
          potential.

7. WHAT TYPES OF SECURITIES MAKE UP THE INCOME COMPONENT OF BALANCED PORTFOLIO'S
   AND GROWTH AND INCOME PORTFOLIO'S HOLDINGS?

          The income component of Balanced Portfolio and Growth and Income
          Portfolio is expected to consist of securities that the portfolio
          managers believe have income potential. Such securities may include
          equity securities, convertible securities and all types of debt
          securities. Equity securities may be included in the income component
          of a Portfolio if they currently pay dividends or the portfolio
          manager believes they have the potential for either increasing their
          dividends or commencing dividends, if none are currently paid.

8. WHAT DOES "LIFE SCIENCE ORIENTATION" MEAN IN RELATION TO GLOBAL LIFE SCIENCES
   PORTFOLIO?

          Generally speaking, the "life sciences" relate to maintaining or
          improving quality of life. So, for example, companies with a "life
          science orientation" include companies engaged in research,
          development, production or distribution of products or services
          related to health and personal care, medicine or pharmaceuticals. Life
          science oriented companies also include companies that the portfolio
          manager believes have growth potential primarily as a result of
          particular products, technology, patents or other market advantages in
          the life sciences. Life sciences encompass a variety of industries,
          including health care, nutrition, agriculture, medical diagnostics,
          nuclear and biochemical research and development and health care
          facilities ownership and operation.

9. HOW DOES GLOBAL TECHNOLOGY PORTFOLIO'S INDUSTRY POLICY DIFFER FROM THAT OF
   GLOBAL LIFE SCIENCES PORTFOLIO?

          Unlike Global Life Sciences Portfolio, Global Technology Portfolio
          will not concentrate its investments in any particular industry or
          group of related industries. As a result, its portfolio manager may
          have more flexibility to find companies that he believes will benefit
          from advances or improvements in technology in a number of industries.
          Nevertheless, the Portfolio may hold a significant portion of its
          assets in industries such as: aerospace/defense; biotechnology;
          computers; office/business equipment; semi-conductors; software;
          telecommunications; and telecommunications equipment.

 12 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES

          Unless otherwise stated, each of the following policies applies to all
          of the Portfolios. The percentage limitations included in these
          policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if a Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When a portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he or she is otherwise
          unable to locate attractive investment opportunities, the Portfolios'
          cash or similar investments may increase. In other words, the
          Portfolios do not always stay fully invested in stocks and bonds. Cash
          or similar investments generally are a residual - they represent the
          assets that remain after a portfolio manager has committed available
          assets to desirable investment opportunities. However, a portfolio
          manager may also temporarily increase a Portfolio's cash position to
          protect its assets or maintain liquidity. Partly because the portfolio
          managers act independently of each other, the cash positions of the
          Portfolios may vary significantly.

          When a Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          The Portfolios invest primarily in domestic and foreign equity
          securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Equity Portfolios also invest in domestic and foreign equity
          securities with varying degrees of emphasis on income. The Portfolios
          may also invest to a lesser degree in other types of securities. These
          securities (which are described in the Glossary) may include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of each Portfolio's
            assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          Each Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolios' Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

            Investment objectives, principal investment strategies and risks  13
<PAGE>

          FOREIGN SECURITIES
          The Portfolios may invest without limit in foreign equity and debt
          securities. The Portfolios may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

          SPECIAL SITUATIONS
          Each Portfolio may invest in special situations. A special situation
          arises when, in the opinion of a Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. A Portfolio's performance could
          suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolios generally intend to purchase securities for long-term
          investment although, to a limited extent, a Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. A Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in a Portfolio's holdings whenever its
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Global Technology Portfolio may invest in companies with relatively
          short product cycles, for example, 6 to 9 months. Consequently its
          portfolio turnover may be more frequent. Increased portfolio turnover
          may result in higher costs for brokerage commissions, dealer mark-ups
          and other transaction costs and may also result in taxable capital
          gains. Higher costs associated with increased portfolio turnover may
          offset gains in a Portfolio's performance.

 14 Janus Aspen Series
<PAGE>

RISKS

          Because the Portfolios may invest substantially all of their assets in
          common stocks, the main risk is the risk that the value of the stocks
          they hold might decrease in response to the activities of an
          individual company or in response to general market and/or economic
          conditions. If this occurs, a Portfolio's share price may also
          decrease. A Portfolio's performance may also be affected by risks
          specific to certain types of investments, such as foreign securities,
          derivative investments, non-investment grade debt securities, initial
          public offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.
          Global Technology Portfolio's performance may also be affected by
          industry risk.

The following questions and answers are designed to help you better understand
some of the risks of investing in the Portfolios.

1. THE PORTFOLIOS MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF AGGRESSIVE GROWTH PORTFOLIO, GLOBAL
   LIFE SCIENCES PORTFOLIO AND GLOBAL TECHNOLOGY PORTFOLIO AFFECT THEIR RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of a Portfolio.

3. HOW COULD THE PORTFOLIOS' INVESTMENTS IN FOREIGN SECURITIES AFFECT THEIR
   PERFORMANCE?

          The Portfolios may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolios' performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as a Portfolio holds a foreign security, its
            value will be affected by the value of the local currency relative
            to the U.S. dollar. When a Portfolio sells a foreign denominated
            security, its value may be worth less in U.S. dollars even if the
            security increases in value in its home country. U.S. dollar
            denominated securities of foreign issuers may also be affected by
            currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and

            Investment objectives, principal investment strategies and risks  15
<PAGE>

            economies based on only a few industries. In some countries, there
            is the risk that the government may take over the assets or
            operations of a company or that the government may impose taxes or
            limits on the removal of a Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

4. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

5. HOW DO THE PORTFOLIOS TRY TO REDUCE RISK?

          The Portfolios may use futures, options, swaps and other derivative
          instruments to "hedge" or protect their portfolios from adverse
          movements in securities prices and interest rates. The Portfolios may
          also use a variety of currency hedging techniques, including forward
          currency contracts, to manage exchange rate risk. The portfolio
          managers believe the use of these instruments will benefit the
          Portfolios. However, a Portfolio's performance could be worse than if
          the Portfolio had not used such instruments if a portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

6. WHAT IS "INDUSTRY RISK"?

          Industry risk is the possibility that a group of related stocks will
          decline in price due to industry-specific developments. Companies in
          the same or similar industries may share common characteristics and
          are more likely to react similarly to industry-specific market or
          economic developments. In the life sciences, for example, many
          companies are subject to government regulation and approval of their
          products and services, which may affect their price or availability.
          In addition, the products and services offered by these companies may
          quickly become obsolete in the face of scientific or technological
          developments. The economic outlook of such companies may fluctuate
          dramatically due to changes in regulatory or competitive environments.
          In technology-related industries, competitive pressures may have a
          significant effect on the performance of companies in which Global
          Technology Portfolio may invest. In addition, technology and
          technology-related companies often progress at an accelerated rate,
          and these companies may be subject to short product cycles and
          aggressive pricing which may increase their volatility.

 16 Janus Aspen Series
<PAGE>

          Global Life Sciences Portfolio invests in a concentrated portfolio,
          which may result in greater exposure to related industries. As a
          result, the Portfolio may be more volatile than a less concentrated
          portfolio. Although Global Technology Portfolio does not "concentrate"
          in a specific group of industries, it may, at times, have significant
          exposure to companies in a variety of technology-related industries.

            Investment objectives, principal investment strategies and risks  17
<PAGE>
Management of the portfolios

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to each of the Portfolios and is responsible
          for the day-to-day management of the investment portfolios and other
          business affairs of the Portfolios.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning each Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolios, and may be reimbursed by the Portfolios for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolios and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolios' Shares
          may perform certain administrative services relating to the Portfolios
          and Janus Capital or the Portfolios may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          Each Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with each Portfolio
          spells out the management fee and other expenses that the Portfolios
          must pay. Each of the Portfolios is subject to the following
          management fee schedule (expressed as an annual rate). In addition,
          the Shares of each Portfolio incur expenses not assumed by Janus
          Capital, including the distribution fee, transfer agent and custodian
          fees and expenses, legal and auditing fees, printing and mailing costs
          of sending reports and other information to existing shareholders, and
          independent Trustees' fees and expenses.

<TABLE>
<CAPTION>
                                                           Average Daily                           Expense
                                                             Net Assets        Annual Rate          Limit
     Fee Schedule                                           of Portfolio      Percentage (%)    Percentage (%)
- -------------------------------------------------------------------------------------------------------------------
     <S>                                                  <C>                 <C>               <C>
     Aggressive Growth Portfolio                          All Asset Levels         0.65                N/A
     Balanced Portfolio
     Growth and Income Portfolio
     International Growth Portfolio
     Worldwide Growth Portfolio
- -------------------------------------------------------------------------------------------------------------------
     Global Life Sciences Portfolio                       All Asset Levels         0.65             1.25(1)
     Global Technology Portfolio
- -------------------------------------------------------------------------------------------------------------------
</TABLE>

(1) Janus Capital has agreed to limit the Portfolios' expenses as indicated
    until at least the next annual renewal of the advisory agreements. As noted
    in the fee table on page 8, however, the Portfolios' expenses without
    waivers are not expected to exceed the expense limit.

          For the fiscal year ended December 31, 1999, each Portfolio paid Janus
          Capital the following management fees based upon each Portfolio's
          average net assets: 0.68% for Aggressive Growth Portfolio, 0.67% for
          Balanced Portfolio, 0.75% for Growth and Income Portfolio, 0.73% for
          International Growth Portfolio and 0.66% for Worldwide Growth
          Portfolio. These rates were based on a higher fee rate that was
          previously in effect for these Portfolios.

 18 Janus Aspen Series
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGERS

LAURENCE J. CHANG
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio which he has
            co-managed since May 1998 and December 1999, respectively. He has
            also co-managed Janus Overseas Fund and Janus Worldwide Fund
            since April 1998 and September 1999, respectively. He served as
            assistant portfolio manager for these funds since 1996. Mr. Chang
            joined Janus Capital in 1993 as a research analyst. He received
            an undergraduate degree with honors in Religion with a
            concentration in Philosophy from Dartmouth College and a Masters
            Degree in Political Science from Stanford University. He has
            earned the right to use the Chartered Financial Analyst
            designation.

DAVID J. CORKINS
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Growth and
            Income Portfolio which he has managed since its inception. He is
            Executive Vice President and portfolio manager of Janus Growth
            and Income Fund which he has managed since August 1997. He is an
            assistant portfolio manager of Janus Mercury Fund. He joined
            Janus in 1995 as a research analyst specializing in domestic
            financial services companies and a variety of foreign industries.
            Prior to joining Janus, he was the Chief Financial Officer of
            Chase U.S. Consumer Services, Inc., a Chase Manhattan mortgage
            business. He holds a Bachelor of Arts in English and Russian from
            Dartmouth and received his Master of Business Administration from
            Columbia University in 1993.

JAMES P. GOFF
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Aggressive
            Growth Portfolio, which he has managed since inception. Mr. Goff
            joined Janus Capital in 1988 and has managed Janus Enterprise
            Fund since its inception. Mr. Goff co-managed or managed Janus
            Venture Fund from December 1993 to February 1997. He holds a
            Bachelor of Arts in Economics from Yale University and he has
            earned the right to use the Chartered Financial Analyst
            designation.

HELEN YOUNG HAYES
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio, which she has
            managed or co-managed since inception. Ms. Hayes joined Janus
            Capital in 1987 and has managed or co-managed Janus Worldwide
            Fund and Janus Overseas Fund since their inceptions. She holds a
            Bachelor of Arts in Economics from Yale University and she has
            earned the right to use the Chartered Financial Analyst
            designation.

                                                Management of the portfolios  19
<PAGE>

C. MIKE LU
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Global
            Technology Portfolio and Janus Global Technology Fund, which he
            has managed since inception. He joined Janus Capital in 1991 as a
            research analyst and has consistently focused on companies in the
            technology industry. Mr. Lu has a Bachelor of Arts in History and
            a Bachelor of Arts in Economics from Yale University. Mr. Lu has
            earned the right to use the Chartered Financial Analyst
            designation.

THOMAS R. MALLEY
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Global Life
            Sciences Portfolio and Janus Global Life Sciences Fund, which he
            has managed since inception. He joined Janus Capital in 1991 as a
            research analyst and has focused on companies in the health care,
            pharmaceutical and biotechnology industries. Mr. Malley has a
            Bachelor of Science in Biology from Stanford University and has
            earned the right to use the Chartered Financial Analyst
            designation.

KAREN L. REIDY
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Balanced
            Portfolio and Equity Income Portfolio as of January 2000, and an
            assistant portfolio manager of Growth Portfolio since 1998. She
            also manages Janus Balanced Fund and Janus Equity Income Fund as
            of January 2000. She is also assistant portfolio manager of Janus
            Fund. Prior to joining Janus Capital in 1995, she worked for
            Price Waterhouse as a manager in both the Mergers and
            Acquisitions and Audit business units. In this capacity, Ms.
            Reidy performed due diligence work for corporate clients and
            oversaw audit engagements. She received an undergraduate degree
            in Accounting from the University of Colorado in 1989 and passed
            the CPA exam in 1992. She has earned the right to use the
            Chartered Financial Analyst designation.

ASSISTANT PORTFOLIO MANAGERS

MATTHEW A. ANKRUM
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            He is also assistant portfolio manager of Janus Enterprise Fund.
            Mr. Ankrum joined Janus Capital as an intern in June 1996, and
            became an equity research analyst in August 1997. Prior to
            joining Janus, Mr. Ankrum worked as a corporate finance analyst
            at William Blair and Company from 1993 through 1995. He was also
            a fixed-income research analyst at Conseco Capital Management.
            Mr. Ankrum has an undergraduate degree in Business Administration
            from the University of Wisconsin and a Master of Business
            Administration from the University of Chicago. Mr. Ankrum has
            earned the right to use the Chartered Financial Analyst
            designation.

 20 Janus Aspen Series
<PAGE>

RON SACHS
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            Mr. Sachs joined Janus Capital in 1996 as a research analyst.
            Prior to coming to Janus, he worked as a consultant for Bain &
            Company and as an attorney for Willkie, Farr & Gallagher. Mr.
            Sachs graduated from Princeton cum laude with an undergraduate
            degree in economics. He obtained his law degree from the
            University of Michigan. Mr. Sachs has earned the right to use the
            Chartered Financial Analyst designation.

                                                Management of the portfolios  21
<PAGE>
Other information

          CLASSES OF SHARES

          Each Portfolio currently offers two or three classes of shares, one of
          which, the Service Shares, are offered pursuant to this prospectus.
          The Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of each
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of certain Portfolios
          are offered only to qualified plans using plan service providers that
          are compensated for providing distribution and/or record keeping and
          other administrative services provided to plan participants. Because
          the expenses of each class may differ, the performance of each class
          is expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, each Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of a Portfolio. Under the terms
          of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolios do not currently anticipate any disadvantages to owners
          of variable insurance contracts because each Portfolio offers its
          shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in one or more Portfolios or substitute
          Shares of another Portfolio. If this occurs, a Portfolio may be forced
          to sell its securities at disadvantageous prices. In addition, the
          Trustees may refuse to sell Shares of any Portfolio to any separate
          account or qualified plan or may suspend or terminate the offering of
          a Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of that Portfolio's
          shareholders. It is possible that a qualified plan investing in the
          Portfolios could lose its qualified plan status under the Internal
          Revenue Code, which could have adverse tax consequences on insurance
          company separate accounts investing in the Shares. Janus Capital
          intends to monitor such qualified plans and the Portfolios may
          discontinue sales to a qualified plan and require plan participants
          with existing investments in the Shares to redeem those investments if
          a plan loses (or in the opinion of Janus Capital is at risk of losing)
          its qualified plan status.

 22 Janus Aspen Series
<PAGE>

          DISTRIBUTION OF EACH PORTFOLIO

          Each Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

                                                           Other information  23
<PAGE>
Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolios, the Internal Revenue Code
          requires each Portfolio to distribute net income and any net gains
          realized on its investments annually. A Portfolio's income from
          dividends and interest and any net realized short-term gains are paid
          to shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of each Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of a Portfolio will automatically be
          reinvested into additional Shares of that Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of a Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of a Portfolio's Shares. The Share price of a Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Aggressive Growth Portfolio declared a dividend in the amount of $0.25
          per share. If the price of Aggressive Growth Portfolio's Shares was
          $10.00 on December 30, the share price on December 31 would be $9.75,
          barring market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolios may be purchased only through
          variable insurance contracts and qualified plans, it is anticipated
          that any income dividends or capital gains distributions made by the
          Shares of a Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIOS

          Dividends, interest and some gains received by the Portfolios on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolios may from year to year make the election
          permitted under Section 853 of the Internal Revenue Code to pass
          through such taxes to shareholders as a foreign tax credit. If such
          election is not made, any foreign taxes paid or accrued will represent
          an expense to the Portfolios which will reduce their investment
          income.

          The Portfolios do not expect to pay any federal income or excise taxes
          because they intend to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of each Portfolio
          are sold in connection with variable insurance contracts, each
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

 24 Janus Aspen Series
<PAGE>
                                                             Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIOS
          DIRECTLY. SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE
          INSURANCE CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING
          INSURANCE COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. CERTAIN
          PORTFOLIOS MAY NOT BE AVAILABLE IN CONNECTION WITH A PARTICULAR
          CONTRACT AND CERTAIN CONTRACTS MAY LIMIT ALLOCATIONS AMONG THE
          PORTFOLIOS. REFER TO THE PROSPECTUS FOR THE PARTICIPATING INSURANCE
          COMPANY'S SEPARATE ACCOUNT OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON
          PURCHASING OR SELLING OF VARIABLE INSURANCE CONTRACTS AND ON HOW TO
          SELECT SPECIFIC PORTFOLIOS AS INVESTMENT OPTIONS FOR A CONTRACT OR A
          QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by a Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolios are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent a Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolios do not price their shares, the NAV of a Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of each Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolios' behalf.

          The Portfolios do not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. Each Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of a Portfolio. Although there is no present intention
          to do so, the Portfolios may discontinue sales of their shares if
          management and the Trustees believe that continued sales may adversely
          affect a Portfolio's ability to achieve its investment objective. If
          sales of a Portfolio's Shares are discontinued, it is expected that
          existing participants invested in that Portfolio would be permitted to
          continue to authorize investment in that Portfolio and to reinvest any
          dividends or capital gains distributions, absent highly unusual
          circumstances. The Portfolios may discontinue sales to a qualified
          plan and require plan participants with existing investments in the
          Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

                                                         Shareholder's guide  25
<PAGE>

          Shares of any Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption proceeds will normally be wired the business day following
          receipt of the redemption order, but in no event later than seven days
          after receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage a Portfolio's investments. The
          Portfolios do not permit frequent trading or market timing. When
          market timing occurs, a Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm a Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash a Portfolio will have to invest. When in
          Janus Capital's opinion such activity would have a disruptive effect
          on portfolio management, a Portfolio reserves the right to refuse
          purchase orders and exchanges into a Portfolio by any person, group or
          commonly controlled account. A Portfolio may notify a market timer of
          rejection of a purchase or exchange order after the day the order is
          placed. If a Portfolio allows a market timer to trade Portfolio
          shares, it may require the market timer to enter into a written
          agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolios that they have
          authorized for investment. Each report will show the investments owned
          by each Portfolio and the market values thereof, as well as other
          information about the Portfolios and their operations. The Trust's
          fiscal year ends December 31.

 26 Janus Aspen Series
<PAGE>
                                                            Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

                                                        Financial highlights  27
<PAGE>
Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolios may
          invest. The Portfolios may invest in these instruments to the extent
          permitted by their investment objectives and policies. The Portfolios
          are not limited by this discussion and may invest in any other types
          of instruments not precluded by the policies discussed elsewhere in
          this Prospectus. Please refer to the SAI for a more detailed
          discussion of certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolios may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, a portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

 28 Janus Aspen Series
<PAGE>

          Portfolios must pay if these investments are profitable, the
          Portfolios may make various elections permitted by the tax laws. These
          elections could require that the Portfolios recognize taxable income,
          which in turn must be distributed, before the securities are sold and
          before cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by a
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, a Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by a
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by a Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

                                                Glossary of investment terms  29
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolios do
          not earn interest on such securities until settlement and bear the
          risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolios may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. They may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolios may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolios may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          A Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

 30 Janus Aspen Series
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolios may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

                                                Glossary of investment terms  31
<PAGE>

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<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolios.

The Statement of Additional Information provides detailed
information about the Portfolios and is incorporated into this
Prospectus by reference. You may review the Portfolios' Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>


                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Growth Portfolio
                              Aggressive Growth Portfolio
                              Capital Appreciation Portfolio
                              Balanced Portfolio
                              International Growth Portfolio
                              Worldwide Growth Portfolio
                              Flexible Income Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                This prospectus describes seven mutual funds (the "Portfolios")
                with a variety of investment objectives, including growth of
                capital, current income and a combination of growth and income.
                Each Portfolio of Janus Aspen Series currently offers two or
                three classes of shares. The Service Shares, (the "Shares"), are
                offered by this prospectus in connection with investment in and
                payments under variable annuity contracts and variable life
                insurance contracts (collectively, "variable insurance
                contracts"), as well as certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. Certain Portfolios may not
                be available in connection with a particular contract and
                certain contracts may limit allocations among the Portfolios.
                See the accompanying contract prospectus for information
                regarding contract fees and expenses and any restrictions on
                purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolios.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Equity Portfolios........................................    2
                   Flexible Income Portfolio................................    7
                   Fees and expenses........................................    9
                INVESTMENT OBJECTIVES, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Equity Portfolios........................................   11
                   Flexible Income Portfolio................................   14
                   General portfolio policies...............................   16
                   Risks for Equity Portfolios..............................   18
                   Risks for Flexible Income Portfolio......................   19
                   Risks Common to all Portfolios...........................   19
                MANAGEMENT OF THE PORTFOLIOS
                   Investment adviser.......................................   21
                   Management expenses and expense limits...................   21
                   Investment personnel.....................................   22
                OTHER INFORMATION...........................................   25
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   27
                   Taxes....................................................   27
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   28
                   Purchases................................................   28
                   Redemptions..............................................   28
                   Frequent trading.........................................   29
                   Shareholder communications...............................   29
                FINANCIAL HIGHLIGHTS........................................   30
                GLOSSARY
                   Glossary of investment terms.............................   31
                RATING CATEGORIES
                   Explanation of rating categories.........................   35

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

EQUITY PORTFOLIOS

          The Equity Portfolios are designed for long-term investors who seek
          growth of capital and who can tolerate the greater risks associated
          with common stock investments.

1. WHAT ARE THE INVESTMENT OBJECTIVES OF THE EQUITY PORTFOLIOS?

- --------------------------------------------------------------------------------

          DOMESTIC EQUITY PORTFOLIOS

          - GROWTH PORTFOLIO seeks long-term growth of capital in a manner
            consistent with the preservation of capital.

          - AGGRESSIVE GROWTH PORTFOLIO AND CAPITAL APPRECIATION PORTFOLIO
            seek long-term growth of capital.

          - BALANCED PORTFOLIO seeks long-term capital growth, consistent
            with preservation of capital and balanced by current income.

          GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          - INTERNATIONAL GROWTH PORTFOLIO seeks long-term growth of capital.

          - WORLDWIDE GROWTH PORTFOLIO seeks long-term growth of capital in a
            manner consistent with the preservation of capital.

          The Portfolios' Trustees may change these objectives without a
          shareholder vote and the Portfolios will notify you of any changes
          that are material. If there is a material change to a Portfolio's
          objective or policies, you should consider whether that Portfolio
          remains an appropriate investment for you. There is no guarantee that
          a Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF THE EQUITY PORTFOLIOS?

          The portfolio managers apply a "bottom up" approach in choosing
          investments. In other words, they look for companies with earnings
          growth potential one at a time. If a portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of a Portfolio's assets may be in cash or similar investments.

          GROWTH PORTFOLIO invests primarily in common stocks selected for their
          growth potential. Although the Portfolio can invest in companies of
          any size, it generally invests in larger, more established companies.

          AGGRESSIVE GROWTH PORTFOLIO invests primarily in common stocks
          selected for their growth potential, and normally invests at least 50%
          of its equity assets in medium-sized companies.

          CAPITAL APPRECIATION PORTFOLIO invests primarily in common stocks
          selected for their growth potential. The Portfolio may invest in
          companies of any size, from larger, well-established companies to
          smaller, emerging growth companies.

          BALANCED PORTFOLIO normally invests 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. The
          Portfolio will normally invest at least 25% of its assets in
          fixed-income securities.

          INTERNATIONAL GROWTH PORTFOLIO normally invests at least 65% of its
          total assets in securities of issuers from at least five different
          countries, excluding the United States. Although the Portfolio intends
          to invest

 2 Janus Aspen Series
<PAGE>

          substantially all of its assets in issuers located outside the United
          States, it may invest in U.S. issuers and it may at times invest all
          of its assets in fewer than five countries, or even a single country.

          WORLDWIDE GROWTH PORTFOLIO invests primarily in common stocks of
          companies of any size throughout the world. The Portfolio normally
          invests in issuers from at least five different countries, including
          the United States. The Portfolio may at times invest in fewer than
          five countries or even a single country.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN THE EQUITY PORTFOLIOS?

          The biggest risk of investing in these Portfolios is that their
          returns may vary, and you could lose money. If you are considering
          investing in any of the Equity Portfolios, remember that they are each
          designed for long-term investors who can accept the risks of investing
          in a portfolio with significant common stock holdings. Common stocks
          tend to be more volatile than other investment choices.

          The value of a Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of a
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of a Portfolio's holdings decreases, that
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in a Portfolio you would get back less money.

          The income component of BALANCED PORTFOLIO includes fixed-income
          securities. A fundamental risk to the income component is that the
          value of these securities will fall if interest rates rise. Generally,
          the value of a fixed-income portfolio will decrease when interest
          rates rise, which means the Portfolio's NAV may likewise decrease.
          Another fundamental risk associated with fixed-income securities is
          credit risk, which is the risk that an issuer of a bond will be unable
          to make principal and interest payments when due.

          INTERNATIONAL GROWTH PORTFOLIO AND WORLDWIDE GROWTH PORTFOLIO may have
          significant exposure to foreign markets. As a result, their returns
          and NAV may be affected to a large degree by fluctuations in currency
          exchange rates or political or economic conditions in a particular
          country.

          AGGRESSIVE GROWTH PORTFOLIO AND CAPITAL APPRECIATION PORTFOLIO are
          nondiversified. In other words, they may hold larger positions in a
          smaller number of securities than a diversified fund. As a result, a
          single security's increase or decrease in value may have a greater
          impact on a Portfolio's NAV and total return.

          An investment in these Portfolios is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in the Equity Portfolios by showing how each of the Equity
          Portfolios' performance has varied over time. The Portfolios' Service
          Shares commenced operations on December 31, 1999. The returns shown
          for the Service Shares of these Portfolios reflect the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses (ignoring any fee and expense
          limitations). The bar charts depict the change in performance from
          year-to-year during the period indicated but do not include charges
          and expenses attributable to any insurance product which would lower
          the performance illustrated. The Portfolios do not impose any sales or
          other charges that would affect total return computations. Total
          return figures include the effect of each Portfolio's expenses. The
          tables compare the average annual returns for the Service Shares of
          each Portfolio for the periods indicated to a broad-based securities
          market index.

                                                          Risk return summary  3
<PAGE>

           GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                              2.71%  29.96%   18.14%   22.49%   35.59%    43.01%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1998  27.71%  Worst Quarter  3rd-1998 (10.95%)

                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Growth Portfolio                                          43.01%    29.53%         23.86%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                                                                      --------------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

           AGGRESSIVE GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                             16.33%  27.38%    7.72%   12.53%   34.19%   123.16%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1999  58.17%  Worst Quarter  3rd-1998 (15.00%)

                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                         1 year     5 years       (9/13/93)
                <S>                                                      <C>        <C>        <C>
                Aggressive Growth Portfolio                              123.16%    35.83%         33.98%
                S&P MidCap 400 Index*                                     14.72%    23.05%         18.08%
                                                                     ---------------------------------------------
</TABLE>

           * The S&P MidCap 400 Index is an unmanaged group of 400 domestic
             stocks chosen for their market size, liquidity and industry group
             representation.

 4 Janus Aspen Series
<PAGE>

           CAPITAL APPRECIATION PORTFOLIO

            Annual Returns for Periods Ended 12/31

                                                                57.91%    64.60%
                                                                 1998      1999

            Best Quarter  4th-1999  40.00%  Worst Quarter  3rd-1998 (9.99%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                           Since Inception
                                                                                 1 year       (5/1/97)
                <S>                                                              <C>       <C>
                Capital Appreciation Portfolio                                   64.60%        56.39%
                S&P 500 Index*                                                   21.03%        27.40%
                                                                             --------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

           BALANCED PORTFOLIO

           Annual Returns for Periods Ended 12/31

                              0.84%  24.79%   16.18%   21.96%   34.03%    26.03%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1998  20.26%  Worst Quarter  3rd-1998 (5.02%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Balanced Portfolio                                        26.03%    24.55%         20.51%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                Lehman Brothers Gov't/Corp Bond Index**                   (2.15%)    7.61%          5.40%
                                                                      --------------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

          ** Lehman Brothers Gov't/Corp Bond Index is composed of all bonds that
             are of investment grade with at least one year until maturity.

                                                          Risk return summary  5
<PAGE>

           INTERNATIONAL GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                                     23.15%   34.71%   18.36%   16.88%    79.52%
                                      1995     1996     1997     1998      1999

           Best Quarter  4th-1999  56.24%  Worst Quarter  3rd-1998 (17.76%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (5/2/94)
                <S>                                                       <C>       <C>        <C>
                International Growth Portfolio                            79.52%    33.17%         28.19%
                Morgan Stanley Capital International EAFE(R) Index*       26.96%    12.83%         11.22%
                                                                      ----------------------------------------
</TABLE>

           * The Morgan Stanley Capital International EAFE(R) Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 20 Developed Market countries in Europe,
             Australasia and the Far East.

           WORLDWIDE GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                              1.53%  27.29%   28.80%   21.91%   28.71%    63.49%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  4th-1999  41.62%  Worst Quarter  3rd-1998 (17.00%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Worldwide Growth Portfolio                                63.49%    33.28%         29.35%
                Morgan Stanley Capital International World Index*         24.93%    19.76%         16.41%
                                                                      --------------------------------------------
</TABLE>

           * The Morgan Stanley Capital International World Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 21 Developed Market countries in North
             America, Europe and the Asia/Pacific Region.

          Since Global Life Sciences Portfolio and Global Technology Portfolio
          did not commence operations until January 15, 2000, there is no
          performance available as of the date of this prospectus.

          The Equity Portfolios' past performance does not necessarily indicate
          how they will perform in the future.

 6 Janus Aspen Series
<PAGE>

FLEXIBLE INCOME PORTFOLIO

          Flexible Income Portfolio is designed for long-term investors who
          primarily seek current income.

1. WHAT IS THE INVESTMENT OBJECTIVE OF FLEXIBLE INCOME PORTFOLIO?

- --------------------------------------------------------------------------------

          - FLEXIBLE INCOME PORTFOLIO seeks to obtain maximum total return,
            consistent with preservation of capital.

          The Trustees may change the objective without a shareholder vote and
          the Portfolio will notify you of any changes that are material. If
          there is a material change to the Portfolio's objective or policies,
          you should consider whether it remains an appropriate investment for
          you. There is no guarantee that the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF FLEXIBLE INCOME PORTFOLIO?

          In addition to considering economic factors such as the effect of
          interest rates on the Portfolio's investments, the portfolio manager
          applies a "bottom up" approach in choosing investments. In other
          words, he looks mostly for income-producing securities that meet their
          investment criteria one at a time. If the portfolio manager is unable
          to find such investments, the Portfolio's assets may be in cash or
          similar investments.

          Flexible Income Portfolio invests primarily in a wide variety of
          income-producing securities such as corporate bonds and notes,
          government securities and preferred stock. As a fundamental policy,
          the Portfolio will invest at least 80% of its assets in
          income-producing securities. The Portfolio may own an unlimited amount
          of high-yield/high-risk bonds, and these securities may be a big part
          of the portfolio.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN FLEXIBLE INCOME PORTFOLIO?

          Although Flexible Income Portfolio may be less volatile than funds
          that invest most of their assets in common stocks, the Portfolio's
          returns and yields will vary, and you could lose money.

          The Portfolio invests in a variety of fixed-income securities. A
          fundamental risk is that the value of these securities will fall if
          interest rates rise. Generally, the value of a fixed-income portfolio
          will decrease when interest rates rise, which means the Portfolio's
          NAV will likewise decrease. Another fundamental risk associated with
          fixed-income funds is credit risk, which is the risk that an issuer
          will be unable to make principal and interest payments when due.

          Flexible Income Portfolio may invest an unlimited amount of its assets
          in high-yield/high-risk bonds, also known as "junk" bonds which may be
          sensitive to economic changes, political changes, or adverse
          developments specific to the company that issued the bond. These bonds
          generally have a greater credit risk than other types of fixed-income
          securities. Because of these factors, the performance and NAV of
          Flexible Income Portfolio may vary significantly, depending upon its
          holdings of junk bonds.

          An investment in the Portfolio is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

                                                          Risk return summary  7
<PAGE>

          The following information provides some indication of the risks of
          investing in Flexible Income Portfolio by showing how Flexible Income
          Portfolio's performance has varied over time. The Portfolio's Service
          Shares commenced operations on December 31, 1999. The returns shown
          for the Service Shares of the Portfolio reflects the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses on (ignoring any fee and expense
          limitations). The bar chart depicts the change in performance from
          year-to-year during the period indicated but does not include charges
          and expenses attributable to any insurance product which would lower
          the performance illustrated. The Portfolio does not impose any sales
          or other charges that would affect total return computations. Total
          return figures include the effect of the Portfolio's expenses. The
          table compares the average annual returns for the Service Shares of
          the Portfolio for the periods indicated to a broad-based securities
          market index.

           FLEXIBLE INCOME PORTFOLIO

           Annual Returns for Periods Ended 12/31

                             (0.91%) 23.86%    9.03%   11.52%    8.85%     1.30%
                              1994    1995     1996     1997     1998      1999

           Best Quarter  2nd-1995  6.71%  Worst Quarter  2nd-1999 (1.27%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Flexible Income Portfolio                                  1.30%    10.68%          8.36%
                Lehman Brothers Gov't/Corp Bond Index*                    (2.15%)    7.61%          5.40%
                                                                      --------------------------------------------
</TABLE>

           * Lehman Brothers Gov't/Corp Bond Index is composed of all bonds that
             are of investment grade with at least one year until maturity.

          Flexible Income Portfolio's past performance does not necessarily
          indicate how it will perform in the future.

 8 Janus Aspen Series
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolios. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of a Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example on the next page
          shows, these costs are borne indirectly by all shareholders.

                                                          Risk return summary  9
<PAGE>

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolios in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. The information shown is based upon estimated gross
          expenses (without the effect of expense offset arrangements) the
          Shares expect to incur in their initial fiscal year. OWNERS OF
          VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE SHARES SHOULD REFER TO
          THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR A DESCRIPTION OF FEES
          AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT REFLECT DEDUCTIONS AT
          THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR ANY CHARGES THAT MAY
          BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                                     Distribution                         Total Annual Fund
                                                   Management           (12b-1)             Other             Operating
                                                       Fee              Fees(1)           Expenses           Expenses(2)
    <S>                                            <C>               <C>                  <C>             <C>
    Growth Portfolio                                  0.65%              0.25%              0.02%               0.92%
    Aggressive Growth Portfolio                       0.65%              0.25%              0.02%               0.92%
    Capital Appreciation Portfolio                    0.65%              0.25%              0.04%               0.94%
    Balanced Portfolio                                0.65%              0.25%              0.02%               0.92%
    International Growth Portfolio                    0.65%              0.25%              0.11%               1.01%
    Worldwide Growth Portfolio                        0.65%              0.25%              0.05%               0.95%
    Flexible Income Portfolio                         0.65%              0.25%              0.07%               0.97%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of each Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolios with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in each of the Portfolios for
   the time periods indicated then redeem all of your shares at the end of
   those periods. The example also assumes that your investment has a 5%
   return each year, and that the Portfolios' operating expenses remain the
   same. Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Growth Portfolio                                               $ 94      $  293
    Aggressive Growth Portfolio                                    $ 94      $  293
    Capital Appreciation Portfolio                                 $ 96      $  300
    Balanced Portfolio                                             $ 94      $  293
    International Growth Portfolio                                 $103      $  322
    Worldwide Growth Portfolio                                     $ 97      $  303
    Flexible Income Portfolio                                      $ 99      $  309
</TABLE>

 10 Janus Aspen Series
<PAGE>
                                     Investment objectives, principal investment
                                                strategies and risks

          Each of the Portfolios has a similar investment objective and similar
          principal investment strategies to a Janus retail fund:

<TABLE>
                  <S>                                              <C>
                  Growth Portfolio                                                 Janus Fund
                  Aggressive Growth Portfolio                           Janus Enterprise Fund
                  Capital Appreciation Portfolio                            Janus Twenty Fund
                  Balanced Portfolio                                      Janus Balanced Fund
                  International Growth Portfolio                          Janus Overseas Fund
                  Worldwide Growth Portfolio                             Janus Worldwide Fund
                  Flexible Income Portfolio                        Janus Flexible Income Fund
</TABLE>

          Although it is anticipated that each Portfolio and its corresponding
          retail fund will hold similar securities, differences in asset size,
          cash flow needs and other factors may result in differences in
          investment performance. The expenses of each Portfolio and its
          corresponding retail fund are expected to differ. The variable
          contract owner will also bear various insurance related costs at the
          insurance company level. You should review the accompanying separate
          account prospectus for a summary of fees and expenses.

EQUITY PORTFOLIOS

          This section takes a closer look at the investment objectives of each
          of the Equity Portfolios, their principal investment strategies and
          certain risks of investing in the Equity Portfolios. Strategies and
          policies that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 18-20 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

INVESTMENT OBJECTIVES AND PRINCIPAL INVESTMENT STRATEGIES

DOMESTIC EQUITY PORTFOLIOS

          GROWTH PORTFOLIO
          Growth Portfolio seeks long-term growth of capital in a manner
          consistent with the preservation of capital. It pursues its objective
          by investing primarily in common stocks selected for their growth
          potential. Although the Portfolio can invest in companies of any size,
          it generally invests in larger, more established companies.

          AGGRESSIVE GROWTH PORTFOLIO
          Aggressive Growth Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential, and normally invests at least 50% of its
          equity assets in medium-sized companies. Medium-sized companies are
          those whose market capitalization falls within the range of companies
          in the S&P MidCap 400 Index. Market capitalization is a commonly used
          measure of the size and value of a company. The market capitalizations
          within the Index will vary, but as of December 31, 1999, they ranged
          from approximately $170 million to $37 billion.

            Investment objectives, principal investment strategies and risks  11
<PAGE>

          CAPITAL APPRECIATION PORTFOLIO
          Capital Appreciation Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential. The Portfolio may invest in companies of
          any size, from larger, well-established companies to smaller, emerging
          growth companies.

          BALANCED PORTFOLIO
          Balanced Portfolio seeks long-term capital growth, consistent with
          preservation of capital and balanced by current income. It pursues its
          objective by normally investing 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. This
          Portfolio normally invests at least 25% of its assets in fixed-income
          securities.

GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          INTERNATIONAL GROWTH PORTFOLIO
          International Growth Portfolio seeks long-term growth of capital.
          Normally, the Portfolio pursues its objective by investing at least
          65% of its total assets in securities of issuers from at least five
          different countries, excluding the United States. Although the
          Portfolio intends to invest substantially all of its assets in issuers
          located outside the United States, it may at times invest in U.S.
          issuers and it may at times invest all of its assets in fewer than
          five countries or even a single country.

          WORLDWIDE GROWTH PORTFOLIO
          Worldwide Growth Portfolio seeks long-term growth of capital in a
          manner consistent with the preservation of capital. It pursues its
          objective by investing primarily in common stocks of companies of any
          size throughout the world. The Portfolio normally invests in issuers
          from at least five different countries, including the United States.
          The Portfolio may at times invest in fewer than five countries or even
          a single country.

The following questions and answers are designed to help you better understand
the Equity Portfolios' principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          Each of the Portfolios may invest substantially all of its assets in
          common stocks if its portfolio manager believes that common stocks
          will appreciate in value. The portfolio managers generally take a
          "bottom up" approach to selecting companies. In other words, they seek
          to identify individual companies with earnings growth potential that
          may not be recognized by the market at large. They make this
          assessment by looking at companies one at a time, regardless of size,
          country of organization, place of principal business activity, or
          other similar selection criteria. Except for Balanced Portfolio,
          realization of income is not a significant consideration when choosing
          investments for the Portfolios. Income realized on the Portfolios'
          investments may be incidental to their objectives. In the case of
          Balanced Portfolio, the portfolio manager may consider dividend-paying
          characteristics to a greater degree in selecting common stock.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio managers seek companies that meet their
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may

 12 Janus Aspen Series
<PAGE>

          warrant greater consideration in selecting foreign securities. There
          are no limitations on the countries in which the Portfolios may invest
          and the Portfolios may at times have significant foreign exposure.

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. As noted previously, market capitalization is
          an important investment criteria for Aggressive Growth Portfolio.
          Although the other Equity Portfolios offered by this Prospectus do not
          emphasize companies of any particular size, Portfolios with a larger
          asset base are more likely to invest in larger, more established
          issuers.

4. HOW ARE ASSETS ALLOCATED BETWEEN THE GROWTH AND INCOME COMPONENTS OF BALANCED
   PORTFOLIO'S HOLDINGS?

          Balanced Portfolio shifts assets between the growth and income
          components of its holdings based on the portfolio manager's analysis
          of relevant market, financial and economic conditions. If the
          portfolio manager believes that growth securities will provide better
          returns than the yields then available or expected on income-producing
          securities, the Portfolio will place a greater emphasis on the growth
          component.

5. WHAT TYPES OF SECURITIES MAKE UP THE GROWTH COMPONENT OF THE BALANCED
   PORTFOLIO'S INVESTMENTS?

          The growth component of Balanced Portfolio is expected to consist
          primarily of common stocks, but may also include warrants, preferred
          stocks or convertible securities selected primarily for their growth
          potential.

6. WHAT TYPES OF SECURITIES MAKE UP THE INCOME COMPONENT OF BALANCED PORTFOLIO'S
   HOLDINGS?

          The income component of Balanced Portfolio is expected to consist of
          securities that the portfolio manager believes have income potential.
          Such securities may include equity securities, convertible securities
          and all types of debt securities. Equity securities may be included in
          the income component of the Portfolio if they currently pay dividends
          or the portfolio manager believes they have the potential for either
          increasing their dividends or commencing dividends, if none are
          currently paid.

            Investment objectives, principal investment strategies and risks  13
<PAGE>

FLEXIBLE INCOME PORTFOLIO

          This section takes a closer look at the investment objective of
          Flexible Income Portfolio, its principal investment strategies and
          certain risks of investing in the Portfolio. Strategies and policies
          that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 19-20 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          In addition to considering economic factors such as the effect of
          interest rates on the Portfolio's investments, the portfolio manager
          applies a "bottom up" approach in choosing investments. In other
          words, he looks mostly for income-producing securities that meet his
          investment criteria one at a time. If the portfolio manager is unable
          to find such investments, much of the Portfolio's assets may be in
          cash or similar investments.

          Flexible Income Portfolio seeks to obtain maximum total return,
          consistent with preservation of capital. It pursues its objective by
          primarily investing in a wide variety of income-producing securities
          such as corporate bonds and notes, government securities and preferred
          stock. As a fundamental policy, the Portfolio will invest at least 80%
          of its assets in income-producing securities. The Portfolio may own an
          unlimited amount of high-yield/high-risk bonds, and these may be a big
          part of the portfolio. This Portfolio generates total return from a
          combination of current income and capital appreciation, but income is
          usually the dominant portion.

The following questions and answers are designed to help you better understand
Flexible Income Portfolio's principal investment strategies.

1. HOW DO INTEREST RATES AFFECT THE VALUE OF MY INVESTMENT?

          Generally, a fixed-income security will increase in value when
          interest rates fall and decrease in value when interest rates rise.
          Longer-term securities are generally more sensitive to interest rate
          changes than shorter-term securities, but they generally offer higher
          yields to compensate investors for the associated risks. High-yield
          bond prices are generally less directly responsive to interest rate
          changes than investment grade issues and may not always follow this
          pattern. A bond fund's average-weighted effective maturity and its
          duration are measures of how the fund may react to interest rate
          changes.

2. HOW DOES FLEXIBLE INCOME PORTFOLIO MANAGE INTEREST RATE RISK?

          Flexible Income Portfolio may vary the average-weighted effective
          maturity of its assets to reflect its portfolio manager's analysis of
          interest rate trends and other factors. The Portfolio's
          average-weighted effective maturity will tend to be shorter when the
          portfolio manager expects interest rates to rise and longer when the
          portfolio manager expects interest rates to fall. The Portfolio may
          also use futures, options and other derivatives to manage interest
          rate risks.

3. WHAT IS MEANT BY THE PORTFOLIO'S "AVERAGE-WEIGHTED EFFECTIVE MATURITY"?

          The stated maturity of a bond is the date when the issuer must repay
          the bond's entire principal value to an investor. Some types of bonds
          may also have an "effective maturity" that is shorter than the stated
          date due to prepayment or call provisions. Securities without
          prepayment or call provisions generally have an effective maturity
          equal to their stated maturity. Dollar-weighted effective maturity is
          calculated by

 14 Janus Aspen Series
<PAGE>

          averaging the effective maturity of bonds held by the Portfolio with
          each effective maturity "weighted" according to the percentage of net
          assets that it represents.

4. WHAT IS MEANT BY THE PORTFOLIO'S "DURATION"?

          A bond's duration indicates the time it will take an investor to
          recoup his investment. Unlike average maturity, duration reflects both
          principal and interest payments. Generally, the higher the coupon rate
          on a bond, the lower its duration will be. The duration of a bond
          portfolio is calculated by averaging the duration of bonds held by a
          fund with each duration "weighted" according to the percentage of net
          assets that it represents. Because duration accounts for interest
          payments, the Portfolio's duration is usually shorter than its average
          maturity.

5. WHAT IS A HIGH-YIELD/HIGH-RISK BOND?

          A high-yield/high-risk bond (also called a "junk" bond) is a bond
          rated below investment grade by major rating agencies (i.e., BB or
          lower by Standard & Poor's or Ba or lower by Moody's) or an unrated
          bond of similar quality. It presents greater risk of default (the
          failure to make timely interest and principal payments) than higher
          quality bonds.

            Investment objectives, principal investment strategies and risks  15
<PAGE>

GENERAL PORTFOLIO POLICIES

          Unless otherwise stated, each of the following policies applies to all
          of the Portfolios. The percentage limitations included in these
          policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if a Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When a portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he or she is otherwise
          unable to locate attractive investment opportunities, the Portfolios'
          cash or similar investments may increase. In other words, the
          Portfolios do not always stay fully invested in stocks and bonds. Cash
          or similar investments generally are a residual - they represent the
          assets that remain after a portfolio manager has committed available
          assets to desirable investment opportunities. However, a portfolio
          manager may also temporarily increase a Portfolio's cash position to
          protect its assets or maintain liquidity. Partly because the portfolio
          managers act independently of each other, the cash positions of the
          Portfolios may vary significantly.

          When a Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          The Equity Portfolios invest primarily in domestic and foreign equity
          securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Equity Portfolios also invest in domestic and foreign equity
          securities with varying degrees of emphasis on income. The Portfolios
          may also invest to a lesser degree in other types of securities. These
          securities (which are described in the Glossary) may include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of each Portfolio's
            assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          Flexible Income Portfolio invests primarily in fixed-income securities
          which may include corporate bonds and notes, government securities,
          preferred stock, high-yield/high-risk fixed-income securities and
          municipal obligations. The Portfolio may also invest to a lesser
          degree in other types of securities. These securities (which are
          described in the Glossary) may include:

          - common stocks

          - mortgage- and asset-backed securities

          - zero coupon, pay-in-kind and step coupon securities

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

 16 Janus Aspen Series
<PAGE>

          ILLIQUID INVESTMENTS
          Each Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolios' Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolios may invest without limit in foreign equity and debt
          securities. The Portfolios may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

          SPECIAL SITUATIONS
          Each Portfolio may invest in special situations. A special situation
          arises when, in the opinion of a Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. A Portfolio's performance could
          suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolios generally intend to purchase securities for long-term
          investment although, to a limited extent, a Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. A Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in a Portfolio's holdings whenever its
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in a Portfolio's
          performance.

            Investment objectives, principal investment strategies and risks  17
<PAGE>

RISKS FOR EQUITY PORTFOLIOS

          Because the Portfolios may invest substantially all of their assets in
          common stocks, the main risk is the risk that the value of the stocks
          they hold might decrease in response to the activities of an
          individual company or in response to general market and/or economic
          conditions. If this occurs, a Portfolio's share price may also
          decrease. A Portfolio's performance may also be affected by risks
          specific to certain types of investments, such as foreign securities,
          derivative investments, non-investment grade debt securities, initial
          public offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in the Equity Portfolios.

1. THE PORTFOLIOS MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF AGGRESSIVE GROWTH PORTFOLIO AND CAPITAL
   APPRECIATION PORTFOLIO AFFECT THEIR RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of a Portfolio.

 18 Janus Aspen Series
<PAGE>

RISKS FOR FLEXIBLE INCOME PORTFOLIO

          Because the Portfolio invests substantially all of its assets in
          fixed-income securities, it is subject to risks such as credit or
          default risks, and decreased value due to interest rate increases. The
          Portfolio's performance may also be affected by risks to certain types
          of investments, such as foreign securities, derivative instruments and
          initial public offerings (IPOs). IPOs and other investment techniques
          may have a magnified performance impact on a portfolio with a small
          asset base. A portfolio may not experience similar performance as its
          assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in Flexible Income Portfolio.

1. WHAT IS MEANT BY "CREDIT QUALITY" AND WHAT ARE THE RISKS ASSOCIATED WITH IT?

          Credit quality measures the likelihood that the issuer will meet its
          obligations on a bond. One of the fundamental risks associated with
          all fixed-income funds is credit risk, which is the risk that an
          issuer will be unable to make principal and interest payments when
          due. U.S. government securities are generally considered to be the
          safest type of investment in terms of credit risk. Municipal
          obligations generally rank between U.S. government securities and
          corporate debt securities in terms of credit safety. Corporate debt
          securities, particularly those rated below investment grade, present
          the highest credit risk.

2. HOW IS CREDIT QUALITY MEASURED?

          Ratings published by nationally recognized statistical rating agencies
          such as Standard & Poor's Ratings Service and Moody's Investors
          Service, Inc. are widely accepted measures of credit risk. The lower a
          bond issue is rated by an agency, the more credit risk it is
          considered to represent. Lower rated bonds generally pay higher yields
          to compensate investors for the associated risk. Please refer to
          "Explanation of Rating Categories" on pages 35-36 for a description of
          rating categories.

RISKS COMMON TO ALL PORTFOLIOS

The following questions and answers discuss risks that apply to all Portfolios.

1. HOW COULD THE PORTFOLIOS' INVESTMENTS IN FOREIGN SECURITIES AFFECT THEIR
   PERFORMANCE?

          The Portfolios may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolios' performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as a Portfolio holds a foreign security, its
            value will be affected by the value of the local currency relative
            to the U.S. dollar. When a Portfolio sells a foreign denominated
            security, its value may be worth less in U.S. dollars even if the
            security increases in value in its home country. U.S. dollar
            denominated securities of foreign issuers may also be affected by
            currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may take over the assets or operations of a company or
            that the government may impose taxes or limits on the removal of a
            Portfolio's assets from that country.

            Investment objectives, principal investment strategies and risks  19
<PAGE>

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

2. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          The junk bond market can experience sudden and sharp price swings.
          Because Flexible Income Portfolio may invest a significant portion of
          its assets in high-yield/high-risk bonds, investors should be willing
          to tolerate a corresponding increase in the risk of significant and
          sudden changes in NAV.

          Please refer to "Explanation of Rating Categories" on pages 35-36 for
          a description of bond rating categories.

3. HOW DO THE PORTFOLIOS TRY TO REDUCE RISK?

          The Portfolios may use futures, options, swaps and other derivative
          instruments to "hedge" or protect their portfolios from adverse
          movements in securities prices and interest rates. The Portfolios may
          also use a variety of currency hedging techniques, including forward
          currency contracts, to manage exchange rate risk. The portfolio
          managers believe the use of these instruments will benefit the
          Portfolios. However, a Portfolio's performance could be worse than if
          the Portfolio had not used such instruments if a portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 20 Janus Aspen Series
<PAGE>
                                                    Management of the portfolios

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to each of the Portfolios and is responsible
          for the day-to-day management of the investment portfolios and other
          business affairs of the Portfolios.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning each Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolios, and may be reimbursed by the Portfolios for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolios and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolios' Shares
          may perform certain administrative services relating to the Portfolios
          and Janus Capital or the Portfolios may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          Each Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with each Portfolio
          spells out the management fee and other expenses that the Portfolios
          must pay. Each of the Portfolios is subject to the following
          management fee schedule (expressed as an annual rate). In addition,
          the Shares of each Portfolio incur expenses not assumed by Janus
          Capital, including the distribution fee, transfer agent and custodian
          fees and expenses, legal and auditing fees, printing and mailing costs
          of sending reports and other information to existing shareholders, and
          independent Trustees' fees and expenses.

<TABLE>
<CAPTION>
                                                          Average Daily
                                                           Net Assets         Annual Rate      Expense Limit
     Fee Schedule                                         of Portfolio       Percentage (%)    Percentage (%)
- ------------------------------------------------------------------------------------------------------------------
<S>                                                     <C>                  <C>               <C>
     Growth Portfolio                                    All Asset Levels         0.65               N/A
     Aggressive Growth Portfolio
     Capital Appreciation Portfolio
     Balanced Portfolio
     International Growth Portfolio
     Worldwide Growth Portfolio
- ------------------------------------------------------------------------------------------------------------------
     Flexible Income Portfolio                          First $300 Million        0.65              1.00(1)
                                                        Over $300 Million         0.55
- ------------------------------------------------------------------------------------------------------------------
</TABLE>

(1) Janus Capital has agreed to limit the Portfolio's expenses as indicated
    until at least the next annual renewal of the advisory agreements. As noted
    in the fee table on page 10, however, the Portfolio's expenses without
    waivers are not expected to exceed the expense limit.

          For the fiscal year ended December 31, 1999, each Portfolio paid Janus
          Capital the following management fees based upon each Portfolio's
          average net assets: 0.67% for Growth Portfolio, 0.68% for Aggressive
          Growth Portfolio, 0.75% for Capital Appreciation Portfolio, 0.67% for
          Balanced Portfolio, 0.73% for International Growth Portfolio, 0.66%
          for Worldwide Growth Portfolio and 0.65% for Flexible Income
          Portfolio. These rates were based on a higher fee rate that was
          previously in effect for certain of these Portfolios.

                                                Management of the portfolios  21
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGERS

LAURENCE J. CHANG
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio which he has
            co-managed since May 1998 and December 1999, respectively. He has
            also co-managed Janus Overseas Fund and Janus Worldwide Fund
            since April 1998 and September 1999, respectively. He served as
            assistant portfolio manager for these funds since 1996. Mr. Chang
            joined Janus Capital in 1993 as a research analyst. He received
            an undergraduate degree with honors in Religion with a
            concentration in Philosophy from Dartmouth College and a Masters
            Degree in Political Science from Stanford University. He has
            earned the right to use the Chartered Financial Analyst
            designation.

JAMES P. GOFF
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Aggressive
            Growth Portfolio, which he has managed since inception. Mr. Goff
            joined Janus Capital in 1988 and has managed Janus Enterprise
            Fund since its inception. Mr. Goff co-managed or managed Janus
            Venture Fund from December 1993 to February 1997. He holds a
            Bachelor of Arts in Economics from Yale University and he has
            earned the right to use the Chartered Financial Analyst
            designation.

HELEN YOUNG HAYES
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio, which she has
            managed or co-managed since inception. Ms. Hayes joined Janus
            Capital in 1987 and has managed or co-managed Janus Worldwide
            Fund and Janus Overseas Fund since their inceptions. She holds a
            Bachelor of Arts in Economics from Yale University and she has
            earned the right to use the Chartered Financial Analyst
            designation.

KAREN L. REIDY
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Balanced
            Portfolio and Equity Income Portfolio as of January 2000, and an
            assistant portfolio manager of Growth Portfolio since 1998. She
            also manages Janus Balanced Fund and Janus Equity Income Fund as
            of January 2000. She is also assistant portfolio manager of Janus
            Fund. Prior to joining Janus Capital in 1995, she worked for
            Price Waterhouse as a manager in both the Mergers and
            Acquisitions and Audit business units. In this capacity, Ms.
            Reidy performed due diligence work for corporate clients and
            oversaw audit engagements. She received an undergraduate degree
            in Accounting from the University of Colorado in 1989 and passed
            the CPA exam in 1992. She has earned the right to use the
            Chartered Financial Analyst designation.

 22 Janus Aspen Series
<PAGE>

BLAINE P. ROLLINS
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Growth
            Portfolio as of January 2000. He previously managed Balanced
            Portfolio from May 1996 to December 1999 and Equity Income
            Portfolio from its inception to December 1999. Mr. Rollins joined
            Janus Capital in 1990 and has managed Janus Fund since January
            2000, Janus Balanced Fund from January 1996 until December 1999
            and Janus Equity Income Fund from inception until December 1999.
            He was an assistant portfolio manager of Janus Fund from January
            1994 until December 1999. He gained experience as a fixed-income
            trader and equity research analyst prior to managing Balanced
            Portfolio. He holds a Bachelor of Science in Finance from the
            University of Colorado and he has earned the right to use the
            Chartered Financial Analyst designation.

SCOTT W. SCHOELZEL
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Capital
            Appreciation Portfolio, which he has managed since its inception.
            He is portfolio manager of Janus Twenty Fund, which he has
            managed since August 1997. He previously managed Janus Olympus
            Fund from its inception to August 1997. Mr. Schoelzel joined
            Janus Capital in January 1994. He holds a Bachelor of Arts in
            Business from Colorado College.

RONALD V. SPEAKER
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Flexible
            Income Portfolio which he has managed or co-managed since its
            inception. He previously served as co-manager of High-Yield
            Portfolio, from its inception to May 1998. He managed Short-Term
            Bond Portfolio from its inception through April 1996. Mr. Speaker
            joined Janus Capital in 1986. He has managed or co-managed Janus
            Flexible Income Fund since December 1991 and previously managed
            both Janus Short-Term Bond Fund and Janus Federal Tax-Exempt Fund
            from inception through December 1995. He previously managed or
            co-managed Janus High-Yield Fund from its inception to February
            1998. He holds a Bachelor of Arts in Finance from the University
            of Colorado and he has earned the right to use the Chartered
            Financial Analyst designation.

            In January 1997, Mr. Speaker settled an SEC administrative action
            involving two personal trades made by him in January of 1993.
            Without admitting or denying the allegations, Mr. Speaker agreed
            to civil money penalty, disgorgement, and interest payments
            totaling $37,199 and to a 90-day suspension which ended on April
            25, 1997.

                                                Management of the portfolios  23
<PAGE>

ASSISTANT PORTFOLIO MANAGERS

MATTHEW A. ANKRUM
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            He is also assistant portfolio manager of Janus Enterprise Fund.
            Mr. Ankrum joined Janus Capital as an intern in June 1996, and
            became an equity research analyst in August 1997. Prior to
            joining Janus, Mr. Ankrum worked as a corporate finance analyst
            at William Blair and Company from 1993 through 1995. He was also
            a fixed-income research analyst at Conseco Capital Management.
            Mr. Ankrum has an undergraduate degree in Business Administration
            from the University of Wisconsin and a Master of Business
            Administration from the University of Chicago. Mr. Ankrum has
            earned the right to use the Chartered Financial Analyst
            designation.

DAVID C. DECKER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. He is also
            an assistant portfolio manager of Janus Fund. He is Executive
            Vice President and portfolio manager of Strategic Value
            Portfolio, Janus Strategic Value Fund and Janus Special
            Situations Fund, each of which he has managed since its
            inception. He obtained a Masters of Business Administration in
            Finance from the Fuqua School of Business at Duke University and
            a Bachelor of Arts in Economics and Political Science from Tufts
            University. Mr. Decker has earned the right to use the Chartered
            Financial Analyst designation.

RON SACHS
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            Mr. Sachs joined Janus Capital in 1996 as a research analyst.
            Prior to coming to Janus, he worked as a consultant for Bain &
            Company and as an attorney for Willkie, Farr & Gallagher. Mr.
            Sachs graduated from Princeton cum laude with an undergraduate
            degree in economics. He obtained his law degree from the
            University of Michigan. Mr. Sachs has earned the right to use the
            Chartered Financial Analyst designation.

JOHN H. SCHREIBER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. Mr.
            Schreiber joined Janus Capital in 1997 as an equity research
            analyst. Prior to coming to Janus he was an equity analyst with
            Fidelity Investments. Mr. Schreiber holds a Bachelor of Science
            degree in mechanical engineering from the University of
            Washington and an MBA from Harvard University.

 24 Janus Aspen Series
<PAGE>
                                                               Other information

          CLASSES OF SHARES

          Each Portfolio currently offers two or three classes of shares, one of
          which, the Service Shares, are offered pursuant to this prospectus.
          The Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of each
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of certain Portfolios
          are offered only to qualified plans using plan service providers that
          are compensated for providing distribution and/or record keeping and
          other administrative services provided to plan participants. Because
          the expenses of each class may differ, the performance of each class
          is expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, each Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of a Portfolio. Under the terms
          of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolios do not currently anticipate any disadvantages to owners
          of variable insurance contracts because each Portfolio offers its
          shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in one or more Portfolios or substitute
          Shares of another Portfolio. If this occurs, a Portfolio may be forced
          to sell its securities at disadvantageous prices. In addition, the
          Trustees may refuse to sell Shares of any Portfolio to any separate
          account or qualified plan or may suspend or terminate the offering of
          a Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of that Portfolio's
          shareholders. It is possible that a qualified plan investing in the
          Portfolios could lose its qualified plan status under the Internal
          Revenue Code, which could have adverse tax consequences on insurance
          company separate accounts investing in the Shares. Janus Capital
          intends to monitor such qualified plans and the Portfolios may
          discontinue sales to a qualified plan and require plan participants
          with existing investments in the Shares to redeem those investments if
          a plan loses (or in the opinion of Janus Capital is at risk of losing)
          its qualified plan status.

                                                           Other information  25
<PAGE>

          DISTRIBUTION OF EACH PORTFOLIO

          Each Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

 26 Janus Aspen Series
<PAGE>
                                                         Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolios, the Internal Revenue Code
          requires each Portfolio to distribute net income and any net gains
          realized on its investments annually. A Portfolio's income from
          dividends and interest and any net realized short-term gains are paid
          to shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of each Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of a Portfolio will automatically be
          reinvested into additional Shares of that Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions, other than daily income dividends, are paid to
          shareholders as of the record date of the distribution of a Portfolio,
          regardless of how long the shares have been held. Undistributed income
          and realized gains are included in the daily NAV of a Portfolio's
          Shares. The Share price of a Portfolio drops by the amount of the
          distribution, net of any subsequent market fluctuations. For example,
          assume that on December 31, the Shares of Growth Portfolio declared a
          dividend in the amount of $0.25 per share. If the price of Growth
          Portfolio's Shares was $10.00 on December 30, the share price on
          December 31 would be $9.75, barring market fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolios may be purchased only through
          variable insurance contracts and qualified plans, it is anticipated
          that any income dividends or capital gains distributions made by the
          Shares of a Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIOS

          Dividends, interest and some gains received by the Portfolios on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolios may from year to year make the election
          permitted under Section 853 of the Internal Revenue Code to pass
          through such taxes to shareholders as a foreign tax credit. If such
          election is not made, any foreign taxes paid or accrued will represent
          an expense to the Portfolios which will reduce their investment
          income.

          The Portfolios do not expect to pay any federal income or excise taxes
          because they intend to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of each Portfolio
          are sold in connection with variable insurance contracts, each
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  27
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIOS
          DIRECTLY. SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE
          INSURANCE CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING
          INSURANCE COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. CERTAIN
          PORTFOLIOS MAY NOT BE AVAILABLE IN CONNECTION WITH A PARTICULAR
          CONTRACT AND CERTAIN CONTRACTS MAY LIMIT ALLOCATIONS AMONG THE
          PORTFOLIOS. REFER TO THE PROSPECTUS FOR THE PARTICIPATING INSURANCE
          COMPANY'S SEPARATE ACCOUNT OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON
          PURCHASING OR SELLING OF VARIABLE INSURANCE CONTRACTS AND ON HOW TO
          SELECT SPECIFIC PORTFOLIOS AS INVESTMENT OPTIONS FOR A CONTRACT OR A
          QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by a Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolios are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent a Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolios do not price their shares, the NAV of a Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of each Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolios' behalf.

          The Portfolios do not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. Each Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of a Portfolio. Although there is no present intention
          to do so, the Portfolios may discontinue sales of their shares if
          management and the Trustees believe that continued sales may adversely
          affect a Portfolio's ability to achieve its investment objective. If
          sales of a Portfolio's Shares are discontinued, it is expected that
          existing participants invested in that Portfolio would be permitted to
          continue to authorize investment in that Portfolio and to reinvest any
          dividends or capital gains distributions, absent highly unusual
          circumstances. The Portfolios may discontinue sales to a qualified
          plan and require plan participants with existing investments in the
          Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

 28 Janus Aspen Series
<PAGE>

          Shares of any Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption proceeds will normally be wired the business day following
          receipt of the redemption order, but in no event later than seven days
          after receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage a Portfolio's investments. The
          Portfolios do not permit frequent trading or market timing. When
          market timing occurs, a Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm a Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash a Portfolio will have to invest. When in
          Janus Capital's opinion such activity would have a disruptive effect
          on portfolio management, a Portfolio reserves the right to refuse
          purchase orders and exchanges into a Portfolio by any person, group or
          commonly controlled account. A Portfolio may notify a market timer of
          rejection of a purchase or exchange order after the day the order is
          placed. If a Portfolio allows a market timer to trade Portfolio
          shares, it may require the market timer to enter into a written
          agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolios that they have
          authorized for investment. Each report will show the investments owned
          by each Portfolio and the market values thereof, as well as other
          information about the Portfolios and their operations. The Trust's
          fiscal year ends December 31.

                                                         Shareholder's guide  29
<PAGE>
Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

 30 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolios may
          invest. The Portfolios may invest in these instruments to the extent
          permitted by their investment objectives and policies. The Portfolios
          are not limited by this discussion and may invest in any other types
          of instruments not precluded by the policies discussed elsewhere in
          this Prospectus. Please refer to the SAI for a more detailed
          discussion of certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolios may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, a portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  31
<PAGE>

          Portfolios must pay if these investments are profitable, the
          Portfolios may make various elections permitted by the tax laws. These
          elections could require that the Portfolios recognize taxable income,
          which in turn must be distributed, before the securities are sold and
          before cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by a
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, a Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by a
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by a Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 32 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolios do
          not earn interest on such securities until settlement and bear the
          risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolios may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. They may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolios may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolios may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          A Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  33
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolios may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 34 Janus Aspen Series
<PAGE>
                                                Explanation of rating categories

          The following is a description of credit ratings issued by two of the
          major credit ratings agencies. Credit ratings evaluate only the safety
          of principal and interest payments, not the market value risk of lower
          quality securities. Credit rating agencies may fail to change credit
          ratings to reflect subsequent events on a timely basis. Although Janus
          Capital considers security ratings when making investment decisions,
          it also performs its own investment analysis and does not rely solely
          on the ratings assigned by credit agencies.

STANDARD & POOR'S
RATINGS SERVICES

<TABLE>
                <S>                          <C>
                BOND RATING                  EXPLANATION
                -----------------------------------------------------------------------------------------
                Investment Grade
                AAA......................... Highest rating; extremely strong capacity to pay principal
                                             and interest.
                AA.......................... High quality; very strong capacity to pay principal and
                                             interest.
                A........................... Strong capacity to pay principal and interest; somewhat more
                                             susceptible to the adverse effects of changing circumstances
                                             and economic conditions.
                BBB......................... Adequate capacity to pay principal and interest; normally
                                             exhibit adequate protection parameters, but adverse economic
                                             conditions or changing circumstances more likely to lead to
                                             a weakened capacity to pay principal and interest than for
                                             higher rated bonds.
                Non-Investment Grade
                BB, B, CCC, CC, C........... Predominantly speculative with respect to the issuer's
                                             capacity to meet required interest and principal payments.
                                             BB - lowest degree of speculation; C - the highest degree of
                                             speculation. Quality and protective characteristics
                                             outweighed by large uncertainties or major risk exposure to
                                             adverse conditions.
                D........................... In default.
</TABLE>

                                            Explanation of rating categories  35
<PAGE>

MOODY'S INVESTORS SERVICE, INC.

<TABLE>
                <S>                          <C>
                BOND RATING                  EXPLANATION
                -----------------------------------------------------------------------------------------
                Investment Grade
                Aaa......................... Highest quality, smallest degree of investment risk.
                Aa.......................... High quality; together with Aaa bonds, they compose the
                                             high-grade bond group.
                A........................... Upper-medium grade obligations; many favorable investment
                                             attributes.
                Baa......................... Medium-grade obligations; neither highly protected nor
                                             poorly secured. Interest and principal appear adequate for
                                             the present but certain protective elements may be lacking
                                             or may be unreliable over any great length of time.
                Non-Investment Grade
                Ba.......................... More uncertain, with speculative elements. Protection of
                                             interest and principal payments not well safeguarded during
                                             good and bad times.
                B........................... Lack characteristics of desirable investment; potentially
                                             low assurance of timely interest and principal payments or
                                             maintenance of other contract terms over time.
                Caa......................... Poor standing, may be in default; elements of danger with
                                             respect to principal or interest payments.
                Ca.......................... Speculative in a high degree; could be in default or have
                                             other marked shortcomings.
                C........................... Lowest-rated; extremely poor prospects of ever attaining
                                             investment standing.
</TABLE>

          Unrated securities will be treated as noninvestment grade securities
          unless a portfolio manager determines that such securities are the
          equivalent of investment grade securities. Securities that have
          received ratings from more than one agency are considered investment
          grade if at least one agency has rated the security investment grade.

 36 Janus Aspen Series
<PAGE>

SECURITIES HOLDINGS BY RATING CATEGORY

          During the fiscal period ended December 31, 1999, the percentage of
          securities holdings for Flexible Income Portfolio by rating category
          based upon a weighted monthly average was:

<TABLE>
<CAPTION>
                FLEXIBLE INCOME PORTFOLIO
                ----------------------------------------------------------------------------------------
                <S>                                                                       <C>
                    BONDS-S&P RATING:
                 AAA                                                                        5%
                 AA                                                                         6%
                 A                                                                         10%
                 BBB                                                                       23%
                 BB                                                                        12%
                 B                                                                         19%
                 CCC                                                                        2%
                 CC                                                                         0%
                 C                                                                          0%
                 Not Rated                                                                  6%
                 Preferred Stock                                                            2%
                 Cash and Options                                                          15%
                 TOTAL                                                                    100%
                ----------------------------------------------------------------------------------------
</TABLE>

          No other Portfolio described in this Prospectus held 5% or more of its
          assets in bonds rated below investment grade for the fiscal period
          ended December 31, 1999.

                                            Explanation of rating categories  37
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolios.

The Statement of Additional Information provides detailed
information about the Portfolios and is incorporated into this
Prospectus by reference. You may review the Portfolios' Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>
                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Growth Portfolio
                              Aggressive Growth Portfolio
                              Balanced Portfolio
                              International Growth Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                This prospectus describes four mutual funds (the "Portfolios")
                with a variety of investment objectives, including growth of
                capital, current income and a combination of growth and income.
                Each Portfolio of Janus Aspen Series currently offers two or
                three classes of shares. The Service Shares, (the "Shares"), are
                offered by this prospectus in connection with investment in and
                payments under variable annuity contracts and variable life
                insurance contracts (collectively, "variable insurance
                contracts"), as well as certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. Certain Portfolios may not
                be available in connection with a particular contract and
                certain contracts may limit allocations among the Portfolios.
                See the accompanying contract prospectus for information
                regarding contract fees and expenses and any restrictions on
                purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolios.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Equity Portfolios........................................    2
                   Fees and expenses........................................    6
                INVESTMENT OBJECTIVES, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Equity Portfolios........................................    7
                   General portfolio policies...............................   10
                   Risks....................................................   12
                MANAGEMENT OF THE PORTFOLIOS
                   Investment adviser.......................................   14
                   Management expenses and expense limits...................   14
                   Investment personnel.....................................   15
                OTHER INFORMATION...........................................   18
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   20
                   Taxes....................................................   20
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   21
                   Purchases................................................   21
                   Redemptions..............................................   21
                   Frequent trading.........................................   22
                   Shareholder communications...............................   22
                FINANCIAL HIGHLIGHTS........................................   23
                GLOSSARY
                   Glossary of investment terms.............................   24

</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

EQUITY PORTFOLIOS

          The Equity Portfolios are designed for long-term investors who seek
          growth of capital and who can tolerate the greater risks associated
          with common stock investments.

1. WHAT ARE THE INVESTMENT OBJECTIVES OF THE EQUITY PORTFOLIOS?

- --------------------------------------------------------------------------------

          DOMESTIC EQUITY PORTFOLIOS

          - GROWTH PORTFOLIO seeks long-term growth of capital in a manner
            consistent with the preservation of capital.

          - AGGRESSIVE GROWTH PORTFOLIO seeks long-term growth of capital.

          - BALANCED PORTFOLIO seeks long-term capital growth, consistent
            with preservation of capital and balanced by current income.

          GLOBAL/INTERNATIONAL EQUITY PORTFOLIO

          - INTERNATIONAL GROWTH PORTFOLIO seeks long-term growth of capital.

          The Portfolios' Trustees may change these objectives without a
          shareholder vote and the Portfolios will notify you of any changes
          that are material. If there is a material change to a Portfolio's
          objective or policies, you should consider whether that Portfolio
          remains an appropriate investment for you. There is no guarantee that
          a Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF THE EQUITY PORTFOLIOS?

          The portfolio managers apply a "bottom up" approach in choosing
          investments. In other words, they look for companies with earnings
          growth potential one at a time. If a portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of a Portfolio's assets may be in cash or similar investments.

          GROWTH PORTFOLIO invests primarily in common stocks selected for their
          growth potential. Although the Portfolio can invest in companies of
          any size, it generally invests in larger, more established companies.

          AGGRESSIVE GROWTH PORTFOLIO invests primarily in common stocks
          selected for their growth potential, and normally invests at least 50%
          of its equity assets in medium-sized companies.

          BALANCED PORTFOLIO normally invests 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. The
          Portfolio will normally invest at least 25% of its assets in
          fixed-income securities.

          INTERNATIONAL GROWTH PORTFOLIO normally invests at least 65% of its
          total assets in securities of issuers from at least five different
          countries, excluding the United States. Although the Portfolio intends
          to invest substantially all of its assets in issuers located outside
          the United States, it may invest in U.S. issuers and it may at times
          invest all of its assets in fewer than five countries, or even a
          single country.

 2 Janus Aspen Series
<PAGE>

3. WHAT ARE THE MAIN RISKS OF INVESTING IN THE EQUITY PORTFOLIOS?

          The biggest risk of investing in these Portfolios is that their
          returns may vary, and you could lose money. If you are considering
          investing in any of the Equity Portfolios, remember that they are each
          designed for long-term investors who can accept the risks of investing
          in a portfolio with significant common stock holdings. Common stocks
          tend to be more volatile than other investment choices.

          The value of a Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of a
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of a Portfolio's holdings decreases, that
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in a Portfolio you would get back less money.

          The income component of the BALANCED PORTFOLIO includes fixed-income
          securities. A fundamental risk to the income component is that the
          value of these securities will fall if interest rates rise. Generally,
          the value of a fixed-income portfolio will decrease when interest
          rates rise, which means the Portfolio's NAV may likewise decrease.
          Another fundamental risk associated with fixed-income securities is
          credit risk, which is the risk that an issuer of a bond will be unable
          to make principal and interest payments when due.

          INTERNATIONAL GROWTH PORTFOLIO may have significant exposure to
          foreign markets. As a result, its returns and NAV may be affected to a
          large degree by fluctuations in currency exchange rates or political
          or economic conditions in a particular country.

          AGGRESSIVE GROWTH PORTFOLIO is nondiversified. In other words, it may
          hold larger positions in a smaller number of securities than a
          diversified fund. As a result, a single security's increase or
          decrease in value may have a greater impact on the Portfolio's NAV and
          total return.

          An investment in these Portfolios is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in the Equity Portfolios by showing how each of the Equity
          Portfolios' performance has varied over time. The Portfolios' Service
          Shares commenced operations on December 31, 1999. The returns shown
          for the Service Shares of these Portfolios reflect the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses (ignoring any fee and expense
          limitations). The bar charts depict the change in performance from
          year-to-year during the period indicated but do not include charges
          and expenses attributable to any insurance product which would lower
          the performance illustrated. The Portfolios do not impose any sales or
          other charges that would affect total return computations. Total
          return figures include the effect of each Portfolio's expenses. The
          tables compare the average annual returns for the Service Shares of
          each Portfolio for the periods indicated to a broad-based securities
          market index.

                                                          Risk return summary  3
<PAGE>

           GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                              2.71%   29.96%   18.14%   22.49%   35.59%   43.01%
                              1994     1995     1996     1997     1998     1999

           Best Quarter 4th-1998 27.71% Worst Quarter 3rd-1998 (10.95%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                   <C>           <C>        <C>
                Growth Portfolio                                          43.01%    29.53%         23.86%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                                                                      --------------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

           AGGRESSIVE GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                             16.33%   27.38%    7.72%   12.53%   34.19%  123.16%
                              1994     1995     1996     1997     1998     1999

           Best Quarter 4th-1999 58.17% Worst Quarter 3rd-1998 (15.00%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                         1 year     5 years       (9/13/93)
                <S>                                                  <C>            <C>        <C>
                Aggressive Growth Portfolio                              123.16%    35.83%         33.86%
                S&P MidCap 400 Index*                                     14.72%    23.05%         18.08%
                                                                     -----------------------------------------
</TABLE>

           * The S&P MidCap 400 Index is an unmanaged group of 400 domestic
             stocks chosen for their market size, liquidity and industry group
             representation.

 4 Janus Aspen Series
<PAGE>

           BALANCED PORTFOLIO

           Annual Returns for Periods Ended 12/31

                              0.84%   24.79%   16.18%   21.96%   34.03%   26.03%
                              1994     1995     1996     1997     1998     1999

           Best Quarter 4th-1998 20.26% Worst Quarter 3rd-1998 (5.02%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                   <C>           <C>        <C>
                Balanced Portfolio                                        26.03%    24.55%         20.51%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                Lehman Brothers Gov't/Corp Bond Index**                   (2.15%)    7.61%          5.40%
                                                                      ----------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

          ** Lehman Brothers Gov't/Corp Bond Index is composed of all bonds that
             are of investment grade with at least one year until maturity.

           INTERNATIONAL GROWTH PORTFOLIO

           Annual Returns for Periods Ended 12/31

                               23.15%   34.71%   18.36%   16.88%   79.52%
                               1995     1996     1997     1998     1999

           Best Quarter 4th-1999 56.24% Worst Quarter 3rd-1998 (17.76%)


                          Average annual total return for periods ended 12/31/99
                 ---------------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (5/2/94)
                <S>                                                   <C>           <C>        <C>
                International Growth Portfolio                            79.52%    33.17%         28.19%
                Morgan Stanley Capital International EAFE(R) Index*       26.96%    12.83%         11.22%
                                                                      ----------------------------------------
</TABLE>

           * The Morgan Stanley Capital International EAFE(R) Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 20 Developed Market countries in Europe,
             Australasia and the Far East.

          The Equity Portfolios' past performance does not necessarily indicate
          how they will perform in the future.

                                                          Risk return summary  5
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolios. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of a Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example below shows, these
          costs are borne indirectly by all shareholders.

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolios in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. The information shown is based upon estimated gross
          expenses (without the effect of expense offset arrangements) the
          Shares expect to incur in their initial fiscal year. OWNERS OF
          VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE SHARES SHOULD REFER TO
          THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR A DESCRIPTION OF FEES
          AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT REFLECT DEDUCTIONS AT
          THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR ANY CHARGES THAT MAY
          BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                    Distribution                  Total Annual
                                      Management       (12b-1)         Other     Fund Operating
                                          Fee          Fees(1)       Expenses      Expenses(2)
    <S>                               <C>           <C>              <C>         <C>
    Growth Portfolio                    0.65%          0.25%           0.02%         0.92%
    Aggressive Growth Portfolio         0.65%          0.25%           0.02%         0.92%
    Balanced Portfolio                  0.65%          0.25%           0.02%         0.92%
    International Growth Portfolio      0.65%          0.25%           0.11%         1.01%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of each Portfolio expects to incur in its initial fiscal
       year. All expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   This example is intended to help you compare the cost of investing in
   the Portfolios with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in each of the Portfolios for
   the time periods indicated then redeem all of your shares at the end of
   those periods. The example also assumes that your investment has a 5%
   return each year, and that the Portfolios' operating expenses remain the
   same. Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Growth Portfolio                                               $ 94       $293
    Aggressive Growth Portfolio                                    $ 94       $293
    Balanced Portfolio                                             $ 94       $293
    International Growth Portfolio                                 $103       $322
</TABLE>

 6 Janus Aspen Series
<PAGE>
                                     Investment objectives, principal investment
                                                strategies and risks

          Each of the Portfolios has a similar investment objective and similar
          principal investment strategies to a Janus retail fund:

<TABLE>
                  <S>                                                   <C>
                  Growth Portfolio                                                 Janus Fund
                  Aggressive Growth Portfolio                           Janus Enterprise Fund
                  Balanced Portfolio                                      Janus Balanced Fund
                  International Growth Portfolio                          Janus Overseas Fund
</TABLE>

          Although it is anticipated that each Portfolio and its corresponding
          retail fund will hold similar securities, differences in asset size,
          cash flow needs and other factors may result in differences in
          investment performance. The expenses of each Portfolio and its
          corresponding retail fund are expected to differ. The variable
          contract owner will also bear various insurance related costs at the
          insurance company level. You should review the accompanying separate
          account prospectus for a summary of fees and expenses.

EQUITY PORTFOLIOS

          This section takes a closer look at the investment objectives of each
          of the Equity Portfolios, their principal investment strategies and
          certain risks of investing in the Equity Portfolios. Strategies and
          policies that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 12-13 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

INVESTMENT OBJECTIVES AND PRINCIPAL INVESTMENT STRATEGIES

DOMESTIC EQUITY PORTFOLIOS

          GROWTH PORTFOLIO
          Growth Portfolio seeks long-term growth of capital in a manner
          consistent with the preservation of capital. It pursues its objective
          by investing primarily in common stocks selected for their growth
          potential. Although the Portfolio can invest in companies of any size,
          it generally invests in larger, more established companies.

          AGGRESSIVE GROWTH PORTFOLIO
          Aggressive Growth Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential, and normally invests at least 50% of its
          equity assets in medium-sized companies. Medium-sized companies are
          those whose market capitalization falls within the range of companies
          in the S&P MidCap 400 Index. Market capitalization is a commonly used
          measure of the size and value of a company. The market capitalizations
          within the Index will vary, but as of December 31, 1999, they ranged
          from approximately $170 million to $37 billion.

          BALANCED PORTFOLIO
          Balanced Portfolio seeks long-term capital growth, consistent with
          preservation of capital and balanced by current income. It pursues its
          objective by normally investing 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. This
          Portfolio normally invests at least 25% of its assets in fixed-income
          securities.

             Investment objectives, principal investment strategies and risks  7
<PAGE>

GLOBAL/INTERNATIONAL EQUITY PORTFOLIO

          INTERNATIONAL GROWTH PORTFOLIO
          International Growth Portfolio seeks long-term growth of capital.
          Normally, the Portfolio pursues its objective by investing at least
          65% of its total assets in securities of issuers from at least five
          different countries, excluding the United States. Although the
          Portfolio intends to invest substantially all of its assets in issuers
          located outside the United States, it may at times invest in U.S.
          issuers and it may at times invest all of its assets in fewer than
          five countries or even a single country.

The following questions and answers are designed to help you better understand
the Equity Portfolios' principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          Each of the Portfolios may invest substantially all of its assets in
          common stocks if its portfolio manager believes that common stocks
          will appreciate in value. The portfolio managers generally take a
          "bottom up" approach to selecting companies. In other words, they seek
          to identify individual companies with earnings growth potential that
          may not be recognized by the market at large. They make this
          assessment by looking at companies one at a time, regardless of size,
          country of organization, place of principal business activity, or
          other similar selection criteria. Except for Balanced Portfolio,
          realization of income is not a significant consideration when choosing
          investments for the Portfolios. Income realized on the Portfolios'
          investments may be incidental to their objectives. In the case of
          Balanced Portfolio, the portfolio manager may consider dividend-paying
          characteristics to a greater degree in selecting common stock.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio managers seek companies that meet their
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolios may invest and
          the Portfolios may at times have significant foreign exposure.

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. As noted previously, market capitalization is
          an important investment criteria for Aggressive Growth Portfolio.
          Although the other Equity Portfolios offered by this Prospectus do not
          emphasize companies of any particular size, Portfolios with a larger
          asset base are more likely to invest in larger, more established
          issuers.

4. HOW ARE ASSETS ALLOCATED BETWEEN THE GROWTH AND INCOME COMPONENTS OF BALANCED
   PORTFOLIO'S HOLDINGS?

          Balanced Portfolio shifts assets between the growth and income
          components of its holdings based on the portfolio manager's analysis
          of relevant market, financial and economic conditions. If the
          portfolio manager believes that growth securities will provide better
          returns than the yields then available or expected on income-producing
          securities, the Portfolio will place a greater emphasis on the growth
          component.

 8 Janus Aspen Series
<PAGE>

5. WHAT TYPES OF SECURITIES MAKE UP THE GROWTH COMPONENT OF THE BALANCED
   PORTFOLIO'S INVESTMENTS?

          The growth component of the Portfolio is expected to consist primarily
          of common stocks, but may also include warrants, preferred stocks or
          convertible securities selected primarily for their growth potential.

6. WHAT TYPES OF SECURITIES MAKE UP THE INCOME COMPONENT OF BALANCED PORTFOLIO'S
   HOLDINGS?

          The income component of Balanced Portfolio is expected to consist of
          securities that the portfolio manager believes have income potential.
          Such securities may include equity securities, convertible securities
          and all types of debt securities. Equity securities may be included in
          the income component of the Portfolio if they currently pay dividends
          or the portfolio manager believes they have the potential for either
          increasing their dividends or commencing dividends, if none are
          currently paid.

             Investment objectives, principal investment strategies and risks  9
<PAGE>

GENERAL PORTFOLIO POLICIES

          Unless otherwise stated, each of the following policies applies to all
          of the Portfolios. The percentage limitations included in these
          policies and elsewhere in this Prospectus apply at the time of
          purchase of the security. So, for example, if a Portfolio exceeds a
          limit as a result of market fluctuations or the sale of other
          securities, it will not be required to dispose of any securities.

          CASH POSITION
          When a portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he or she is otherwise
          unable to locate attractive investment opportunities, the Portfolios'
          cash or similar investments may increase. In other words, the
          Portfolios do not always stay fully invested in stocks and bonds. Cash
          or similar investments generally are a residual - they represent the
          assets that remain after a portfolio manager has committed available
          assets to desirable investment opportunities. However, a portfolio
          manager may also temporarily increase a Portfolio's cash position to
          protect its assets or maintain liquidity. Partly because the portfolio
          managers act independently of each other, the cash positions of the
          Portfolios may vary significantly.

          When a Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          The Equity Portfolios invest primarily in domestic and foreign equity
          securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Equity Portfolios also invest in domestic and foreign equity
          securities with varying degrees of emphasis on income. The Portfolios
          may also invest to a lesser degree in other types of securities. These
          securities (which are described in the Glossary) may include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of each Portfolio's
            assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          Each Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolios' Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolios may invest without limit in foreign equity and debt
          securities. The Portfolios may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United

 10 Janus Aspen Series
<PAGE>

          States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

          SPECIAL SITUATIONS
          Each Portfolio may invest in special situations. A special situation
          arises when, in the opinion of a Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. A Portfolio's performance could
          suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolios generally intend to purchase securities for long-term
          investment although, to a limited extent, a Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. A Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in a Portfolio's holdings whenever its
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in a Portfolio's
          performance.

            Investment objectives, principal investment strategies and risks  11
<PAGE>

RISKS

          Because the Portfolios may invest substantially all of their assets in
          common stocks, the main risk is the risk that the value of the stocks
          they hold might decrease in response to the activities of an
          individual company or in response to general market and/or economic
          conditions. If this occurs, a Portfolio's share price may also
          decrease. A Portfolio's performance may also be affected by risks
          specific to certain types of investments, such as foreign securities,
          derivative investments, non-investment grade debt securities, initial
          public offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in the Portfolios.

1. THE PORTFOLIOS MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF AGGRESSIVE GROWTH PORTFOLIO AFFECT ITS
   RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of the Portfolio.

3. HOW COULD THE PORTFOLIOS' INVESTMENTS IN FOREIGN SECURITIES AFFECT THEIR
   PERFORMANCE?

          The Portfolios may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolios' performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as a Portfolio holds a foreign security, its
            value will be affected by the value of the local currency relative
            to the U.S. dollar. When a Portfolio sells a foreign denominated
            security, its value may be worth less in U.S. dollars even if the
            security increases in value in its home country. U.S. dollar
            denominated securities of foreign issuers may also be affected by
            currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may

 12 Janus Aspen Series
<PAGE>

            take over the assets or operations of a company or that the
            government may impose taxes or limits on the removal of a
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

4. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

5. HOW DO THE PORTFOLIOS TRY TO REDUCE RISK?

          The Portfolios may use futures, options, swaps and other derivative
          instruments to "hedge" or protect their portfolios from adverse
          movements in securities prices and interest rates. The Portfolios may
          also use a variety of currency hedging techniques, including forward
          currency contracts, to manage exchange rate risk. The portfolio
          managers believe the use of these instruments will benefit the
          Portfolios. However, a Portfolio's performance could be worse than if
          the Portfolio had not used such instruments if a portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

            Investment objectives, principal investment strategies and risks  13
<PAGE>
Management of the portfolios

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to each of the Portfolios and is responsible
          for the day-to-day management of the investment portfolios and other
          business affairs of the Portfolios.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning each Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolios, and may be reimbursed by the Portfolios for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolios and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolios' Shares
          may perform certain administrative services relating to the Portfolios
          and Janus Capital or the Portfolios may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          Each Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with each Portfolio
          spells out the management fee and other expenses that the Portfolios
          must pay. Each of the Portfolios is subject to the following
          management fee schedule (expressed as an annual rate). In addition,
          the Shares of each Portfolio incur expenses not assumed by Janus
          Capital, including the distribution fee, transfer agent and custodian
          fees and expenses, legal and auditing fees, printing and mailing costs
          of sending reports and other information to existing shareholders, and
          independent Trustees' fees and expenses.

<TABLE>
<CAPTION>
                                                                     Average Daily
                                                                      Net Assets         Annual Rate
     Fee Schedule                                                    of Portfolio       Percentage (%)
- ----------------------------------------------------------------------------------------------------------
<S>                                                                 <C>                 <C>
     Growth Portfolio                                               All Asset Levels         0.65
     Aggressive Growth Portfolio
     Balanced Portfolio
     International Growth Portfolio
- -----------------------------------------------------------------------------------------------------------
</TABLE>

          For the fiscal year ended December 31, 1999, each Portfolio paid Janus
          Capital the following management fees based upon each Portfolio's
          average net assets: 0.67% for Growth Portfolio, 0.68% for Aggressive
          Growth Portfolio, 0.67% for Balanced Portfolio and 0.73% for
          International Growth Portfolio. These rates were based on a higher fee
          rate that was previously in effect for these Portfolios.

 14 Janus Aspen Series
<PAGE>

INVESTMENT PERSONNEL

PORTFOLIO MANAGERS

LAURENCE J. CHANG
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio which he has
            co-managed since May 1998 and December 1999, respectively. He has
            also co-managed Janus Overseas Fund and Janus Worldwide Fund
            since April 1998 and September 1999, respectively. He served as
            assistant portfolio manager for these funds since 1996. Mr. Chang
            joined Janus Capital in 1993 as a research analyst. He received
            an undergraduate degree with honors in Religion with a
            concentration in Philosophy from Dartmouth College and a Masters
            Degree in Political Science from Stanford University. He has
            earned the right to use the Chartered Financial Analyst
            designation.

JAMES P. GOFF
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Aggressive
            Growth Portfolio, which he has managed since inception. Mr. Goff
            joined Janus Capital in 1988 and has managed Janus Enterprise
            Fund since its inception. Mr. Goff co-managed or managed Janus
            Venture Fund from December 1993 to February 1997. He holds a
            Bachelor of Arts in Economics from Yale University and he has
            earned the right to use the Chartered Financial Analyst
            designation.

HELEN YOUNG HAYES
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio, which she has
            managed or co-managed since inception. Ms. Hayes joined Janus
            Capital in 1987 and has managed or co-managed Janus Worldwide
            Fund and Janus Overseas Fund since their inceptions. She holds a
            Bachelor of Arts in Economics from Yale University and she has
            earned the right to use the Chartered Financial Analyst
            designation.

KAREN L. REIDY
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Balanced
            Portfolio and Equity Income Portfolio as of January 2000, and an
            assistant portfolio manager of Growth Portfolio since 1998. She
            also manages Janus Balanced Fund and Janus Equity Income Fund as
            of January 2000. She is also assistant portfolio manager of Janus
            Fund. Prior to joining Janus Capital in 1995, she worked for
            Price Waterhouse as a manager in both the Mergers and
            Acquisitions and Audit business units. In this capacity, Ms.
            Reidy performed due diligence work for corporate clients and
            oversaw audit engagements. She received an undergraduate degree
            in Accounting from the University of Colorado in 1989 and passed
            the CPA exam in 1992. She has earned the right to use the
            Chartered Financial Analyst designation.

                                                Management of the portfolios  15
<PAGE>

BLAINE P. ROLLINS
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Growth
            Portfolio as of January 2000. He previously managed Balanced
            Portfolio from May 1996 to December 1999 and Equity Income
            Portfolio from its inception to December 1999. Mr. Rollins joined
            Janus Capital in 1990 and has managed Janus Fund since January
            2000, Janus Balanced Fund from January 1996 until December 1999
            and Janus Equity Income Fund from inception until December 1999.
            He was an assistant portfolio manager of Janus Fund from January
            1994 until December 1999. He gained experience as a fixed-income
            trader and equity research analyst prior to managing Balanced
            Portfolio. He holds a Bachelor of Science in Finance from the
            University of Colorado and he has earned the right to use the
            Chartered Financial Analyst designation.

ASSISTANT PORTFOLIO MANAGERS

MATTHEW A. ANKRUM
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            He is also assistant portfolio manager of Janus Enterprise Fund.
            Mr. Ankrum joined Janus Capital as an intern in June 1996, and
            became an equity research analyst in August 1997. Prior to
            joining Janus, Mr. Ankrum worked as a corporate finance analyst
            at William Blair and Company from 1993 through 1995. He was also
            a fixed-income research analyst at Conseco Capital Management.
            Mr. Ankrum has an undergraduate degree in Business Administration
            from the University of Wisconsin and a Master of Business
            Administration from the University of Chicago. Mr. Ankrum has
            earned the right to use the Chartered Financial Analyst
            designation.

DAVID C. DECKER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. He is also
            an assistant portfolio manager of Janus Fund. He is Executive
            Vice President and portfolio manager of Strategic Value
            Portfolio, Janus Strategic Value Fund and Janus Special
            Situations Fund, each of which he has managed since its
            inception. He obtained a Masters of Business Administration in
            Finance from the Fuqua School of Business at Duke University and
            a Bachelor of Arts in Economics and Political Science from Tufts
            University. Mr. Decker has earned the right to use the Chartered
            Financial Analyst designation.

RON SACHS
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            Mr. Sachs joined Janus Capital in 1996 as a research analyst.
            Prior to coming to Janus, he worked as a consultant for Bain &
            Company and as an attorney for Willkie, Farr & Gallagher. Mr.
            Sachs graduated from Princeton cum laude with an undergraduate
            degree in economics. He obtained his law degree from the
            University of Michigan. Mr. Sachs has earned the right to use the
            Chartered Financial Analyst designation.

 16 Janus Aspen Series
<PAGE>

JOHN H. SCHREIBER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. Mr.
            Schreiber joined Janus Capital in 1997 as an equity research
            analyst. Prior to coming to Janus he was an equity analyst with
            Fidelity Investments. Mr. Schreiber holds a Bachelor of Science
            degree in mechanical engineering from the University of
            Washington and an MBA from Harvard University.

                                                Management of the portfolios  17
<PAGE>
Other information

          CLASSES OF SHARES

          Each Portfolio currently offers two or three classes of shares, one of
          which, the Service Shares, are offered pursuant to this prospectus.
          The Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of each
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of certain Portfolios
          are offered only to qualified plans using plan service providers that
          are compensated for providing distribution and/or record keeping and
          other administrative services provided to plan participants. Because
          the expenses of each class may differ, the performance of each class
          is expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, each Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of a Portfolio. Under the terms
          of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolios do not currently anticipate any disadvantages to owners
          of variable insurance contracts because each Portfolio offers its
          shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in one or more Portfolios or substitute
          Shares of another Portfolio. If this occurs, a Portfolio may be forced
          to sell its securities at disadvantageous prices. In addition, the
          Trustees may refuse to sell Shares of any Portfolio to any separate
          account or qualified plan or may suspend or terminate the offering of
          a Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of that Portfolio's
          shareholders. It is possible that a qualified plan investing in the
          Portfolios could lose its qualified plan status under the Internal
          Revenue Code, which could have adverse tax consequences on insurance
          company separate accounts investing in the Shares. Janus Capital
          intends to monitor such qualified plans and the Portfolios may
          discontinue sales to a qualified plan and require plan participants
          with existing investments in the Shares to redeem those investments if
          a plan loses (or in the opinion of Janus Capital is at risk of losing)
          its qualified plan status.

 18 Janus Aspen Series
<PAGE>

          DISTRIBUTION OF EACH PORTFOLIO

          Each Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

                                                           Other information  19
<PAGE>
Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolios, the Internal Revenue Code
          requires each Portfolio to distribute net income and any net gains
          realized on its investments annually. A Portfolio's income from
          dividends and interest and any net realized short-term gains are paid
          to shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

          Each class of each Portfolio distributes substantially all of its
          investment income at least semi-annually and its net realized gains,
          if any, at least annually. All dividends and capital gains
          distributions from Shares of a Portfolio will automatically be
          reinvested into additional Shares of that Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions are paid to shareholders as of the record date of the
          distribution of a Portfolio, regardless of how long the shares have
          been held. Undistributed income and realized gains are included in the
          daily NAV of a Portfolio's Shares. The Share price of a Portfolio
          drops by the amount of the distribution, net of any subsequent market
          fluctuations. For example, assume that on December 31, the Shares of
          Growth Portfolio declared a dividend in the amount of $0.25 per share.
          If the price of Growth Portfolio's Shares was $10.00 on December 30,
          the share price on December 31 would be $9.75, barring market
          fluctuations.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolios may be purchased only through
          variable insurance contracts and qualified plans, it is anticipated
          that any income dividends or capital gains distributions made by the
          Shares of a Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIOS

          Dividends, interest and some gains received by the Portfolios on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolios may from year to year make the election
          permitted under Section 853 of the Internal Revenue Code to pass
          through such taxes to shareholders as a foreign tax credit. If such
          election is not made, any foreign taxes paid or accrued will represent
          an expense to the Portfolios which will reduce their investment
          income.

          The Portfolios do not expect to pay any federal income or excise taxes
          because they intend to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of each Portfolio
          are sold in connection with variable insurance contracts, each
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

 20 Janus Aspen Series
<PAGE>
                                                            Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIOS
          DIRECTLY. SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE
          INSURANCE CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING
          INSURANCE COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. CERTAIN
          PORTFOLIOS MAY NOT BE AVAILABLE IN CONNECTION WITH A PARTICULAR
          CONTRACT AND CERTAIN CONTRACTS MAY LIMIT ALLOCATIONS AMONG THE
          PORTFOLIOS. REFER TO THE PROSPECTUS FOR THE PARTICIPATING INSURANCE
          COMPANY'S SEPARATE ACCOUNT OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON
          PURCHASING OR SELLING OF VARIABLE INSURANCE CONTRACTS AND ON HOW TO
          SELECT SPECIFIC PORTFOLIOS AS INVESTMENT OPTIONS FOR A CONTRACT OR A
          QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by a Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolios are valued at
          market value or, if a market quotation is not readily available, at
          their fair value determined in good faith under procedures established
          by and under the supervision of the Trustees. Short-term instruments
          maturing within 60 days are valued at amortized cost, which
          approximates market value. See the SAI for more detailed information.

          To the extent a Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolios do not price their shares, the NAV of a Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of each Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolios' behalf.

          The Portfolios do not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. Each Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of a Portfolio. Although there is no present intention
          to do so, the Portfolios may discontinue sales of their shares if
          management and the Trustees believe that continued sales may adversely
          affect a Portfolio's ability to achieve its investment objective. If
          sales of a Portfolio's Shares are discontinued, it is expected that
          existing participants invested in that Portfolio would be permitted to
          continue to authorize investment in that Portfolio and to reinvest any
          dividends or capital gains distributions, absent highly unusual
          circumstances. The Portfolios may discontinue sales to a qualified
          plan and require plan participants with existing investments in the
          Shares to redeem those investments if the plan loses (or in the
          opinion of Janus Capital, is at risk of losing) its qualified plan
          status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

                                                         Shareholder's guide  21
<PAGE>

          Shares of any Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption proceeds will normally be wired the business day following
          receipt of the redemption order, but in no event later than seven days
          after receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage a Portfolio's investments. The
          Portfolios do not permit frequent trading or market timing. When
          market timing occurs, a Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm a Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash a Portfolio will have to invest. When in
          Janus Capital's opinion such activity would have a disruptive effect
          on portfolio management, a Portfolio reserves the right to refuse
          purchase orders and exchanges into a Portfolio by any person, group or
          commonly controlled account. A Portfolio may notify a market timer of
          rejection of a purchase or exchange order after the day the order is
          placed. If a Portfolio allows a market timer to trade Portfolio
          shares, it may require the market timer to enter into a written
          agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolios that they have
          authorized for investment. Each report will show the investments owned
          by each Portfolio and the market values thereof, as well as other
          information about the Portfolios and their operations. The Trust's
          fiscal year ends December 31.

 22 Janus Aspen Series
<PAGE>
                                                           Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

                                                        Financial highlights  23
<PAGE>
Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolios may
          invest. The Portfolios may invest in these instruments to the extent
          permitted by their investment objectives and policies. The Portfolios
          are not limited by this discussion and may invest in any other types
          of instruments not precluded by the policies discussed elsewhere in
          this Prospectus. Please refer to the SAI for a more detailed
          discussion of certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolios may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, a portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

 24 Janus Aspen Series
<PAGE>

          Portfolios must pay if these investments are profitable, the
          Portfolios may make various elections permitted by the tax laws. These
          elections could require that the Portfolios recognize taxable income,
          which in turn must be distributed, before the securities are sold and
          before cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by a
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, a Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by a
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by a Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

                                                Glossary of investment terms  25
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolios do
          not earn interest on such securities until settlement and bear the
          risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolios may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. They may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolios may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolios may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          A Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

 26 Janus Aspen Series
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolios may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

                                                Glossary of investment terms  27
<PAGE>

                       This page intentionally left blank
<PAGE>

[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolios.

The Statement of Additional Information provides detailed
information about the Portfolios and is incorporated into this
Prospectus by reference. You may review the Portfolios' Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736
<PAGE>


                                         [JANUS LOGO]

                   Janus Aspen Series
                   Service Shares

                              PROSPECTUS
                              MAY 1, 2000
                              Growth Portfolio
                              Aggressive Growth Portfolio
                              Capital Appreciation Portfolio
                              Balanced Portfolio
                              Equity Income Portfolio
                              International Growth Portfolio
                              Worldwide Growth Portfolio
                              Money Market Portfolio

                   THE SECURITIES AND EXCHANGE COMMISSION HAS NOT APPROVED OR
                   DISAPPROVED OF THESE SECURITIES OR PASSED ON THE ACCURACY OR
                   ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
                   CONTRARY IS A CRIMINAL OFFENSE.
<PAGE>

    [JANUS LOGO]

                This prospectus describes eight mutual funds (the "Portfolios")
                with a variety of investment objectives, including growth of
                capital, current income and a combination of growth and income.
                Each Portfolio of Janus Aspen Series currently offers two or
                three classes of shares. The Service Shares, (the "Shares"), are
                offered by this prospectus in connection with investment in and
                payments under variable annuity contracts and variable life
                insurance contracts (collectively, "variable insurance
                contracts"), as well as certain qualified retirement plans.

                Janus Aspen Series sells and redeems its Shares at net asset
                value without sales charges, commissions or redemption fees.
                Each variable insurance contract involves fees and expenses that
                are not described in this Prospectus. Certain Portfolios may not
                be available in connection with a particular contract and
                certain contracts may limit allocations among the Portfolios.
                See the accompanying contract prospectus for information
                regarding contract fees and expenses and any restrictions on
                purchases or allocations.

                This prospectus contains information that a prospective
                purchaser of a variable insurance contract or plan participant
                should consider in conjunction with the accompanying separate
                account prospectus of the specific insurance company product
                before allocating purchase payments or premiums to the
                Portfolios.
<PAGE>

                                                               Table of contents

<TABLE>
                <S>                                                           <C>
                RISK/RETURN SUMMARY
                   Equity Portfolios........................................    2
                   Money Market Portfolio...................................    7
                   Fees and expenses........................................    9
                INVESTMENT OBJECTIVES, PRINCIPAL INVESTMENT STRATEGIES AND
                RISKS
                   Equity Portfolios........................................   11
                   General portfolio policies of the Portfolios other than
                   Money Market Portfolio...................................   15
                   Risks for Equity Portfolios..............................   17
                   Money Market Portfolio...................................   19
                MANAGEMENT OF THE PORTFOLIOS
                   Investment adviser.......................................   22
                   Management expenses and expense limits...................   22
                   Investment personnel.....................................   23
                OTHER INFORMATION...........................................   27
                DISTRIBUTIONS AND TAXES
                   Distributions............................................   29
                   Portfolios other than Money Market Portfolio.............   29
                   Money Market Portfolio...................................   29
                   Taxes....................................................   29
                SHAREHOLDER'S GUIDE
                   Pricing of portfolio shares..............................   31
                   Purchases................................................   31
                   Redemptions..............................................   32
                   Frequent trading.........................................   32
                   Shareholder communications...............................   32
                FINANCIAL HIGHLIGHTS........................................   33
                GLOSSARY
                   Glossary of investment terms.............................   34
</TABLE>

                                                            Table of contents  1
<PAGE>
Risk return summary

EQUITY PORTFOLIOS

          The Equity Portfolios are designed for long-term investors who seek
          growth of capital and who can tolerate the greater risks associated
          with common stock investments.

1. WHAT ARE THE INVESTMENT OBJECTIVES OF THE EQUITY PORTFOLIOS?

- --------------------------------------------------------------------------------

          DOMESTIC EQUITY PORTFOLIOS

          - GROWTH PORTFOLIO seeks long-term growth of capital in a manner
            consistent with the preservation of capital.

          - AGGRESSIVE GROWTH PORTFOLIO AND CAPITAL APPRECIATION PORTFOLIO
            seek long-term growth of capital.

          - BALANCED PORTFOLIO seeks long-term capital growth, consistent
            with preservation of capital and balanced by current income.

          - EQUITY INCOME PORTFOLIO seeks current income and long-term growth
            of capital.

          GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          - INTERNATIONAL GROWTH PORTFOLIO seeks long-term growth of capital.

          - WORLDWIDE GROWTH PORTFOLIO seeks long-term growth of capital in a
            manner consistent with the preservation of capital.

          The Portfolios' Trustees may change these objectives without a
          shareholder vote and the Portfolios will notify you of any changes
          that are material. If there is a material change to a Portfolio's
          objective or policies, you should consider whether that Portfolio
          remains an appropriate investment for you. There is no guarantee that
          a Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF THE EQUITY PORTFOLIOS?

          The portfolio managers apply a "bottom up" approach in choosing
          investments. In other words, they look for companies with earnings
          growth potential one at a time. If a portfolio manager is unable to
          find investments with earnings growth potential, a significant portion
          of a Portfolio's assets may be in cash or similar investments.

          GROWTH PORTFOLIO invests primarily in common stocks selected for their
          growth potential. Although the Portfolio can invest in companies of
          any size, it generally invests in larger, more established companies.

          AGGRESSIVE GROWTH PORTFOLIO invests primarily in common stocks
          selected for their growth potential, and normally invests at least 50%
          of its equity assets in medium-sized companies.

          CAPITAL APPRECIATION PORTFOLIO invests primarily in common stocks
          selected for their growth potential. The Portfolio may invest in
          companies of any size, from larger, well-established companies to
          smaller, emerging growth companies.

          BALANCED PORTFOLIO normally invests 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. The
          Portfolio will normally invest at least 25% of its assets in
          fixed-income securities.

 2 Janus Aspen Series
<PAGE>

          EQUITY INCOME PORTFOLIO normally emphasizes investments in common
          stocks, and growth potential is a significant investment
          consideration. Normally, it invests at least 65% of its assets in
          income-producing equity securities.

          INTERNATIONAL GROWTH PORTFOLIO normally invests at least 65% of its
          total assets in securities of issuers from at least five different
          countries, excluding the United States. Although the Portfolio intends
          to invest substantially all of its assets in issuers located outside
          the United States, it may invest in U.S. issuers and it may at times
          invest all of its assets in fewer than five countries, or even a
          single country.

          WORLDWIDE GROWTH PORTFOLIO invests primarily in common stocks of
          companies of any size throughout the world. The Portfolio normally
          invests in issuers from at least five different countries, including
          the United States. The Portfolio may at times invest in fewer than
          five countries or even a single country.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN THE EQUITY PORTFOLIOS?

          The biggest risk of investing in these Portfolios is that their
          returns may vary, and you could lose money. If you are considering
          investing in any of the Equity Portfolios, remember that they are each
          designed for long-term investors who can accept the risks of investing
          in a portfolio with significant common stock holdings. Common stocks
          tend to be more volatile than other investment choices.

          The value of a Portfolio's holdings may decrease if the value of an
          individual company in the portfolio decreases. The value of a
          Portfolio's holdings could also decrease if the stock market goes
          down. If the value of a Portfolio's holdings decreases, that
          Portfolio's net asset value (NAV) will also decrease, which means if
          you sell your shares in a Portfolio you would get back less money.

          The income component of the BALANCED PORTFOLIO AND EQUITY INCOME
          PORTFOLIO includes fixed-income securities. A fundamental risk to the
          income component is that the value of these securities will fall if
          interest rates rise. Generally, the value of a fixed-income portfolio
          will decrease when interest rates rise, which means the Portfolio's
          NAV may likewise decrease. Another fundamental risk associated with
          fixed-income securities is credit risk, which is the risk that an
          issuer of a bond will be unable to make principal and interest
          payments when due.

          INTERNATIONAL GROWTH PORTFOLIO AND WORLDWIDE GROWTH PORTFOLIO may have
          significant exposure to foreign markets. As a result, their returns
          and NAV may be affected to a large degree by fluctuations in currency
          exchange rates or political or economic conditions in a particular
          country.

          AGGRESSIVE GROWTH PORTFOLIO AND CAPITAL APPRECIATION PORTFOLIO, are
          nondiversified. In other words, they may hold larger positions in a
          smaller number of securities than a diversified fund. As a result, a
          single security's increase or decrease in value may have a greater
          impact on a Portfolio's NAV and total return.

          An investment in these Portfolios is not a bank deposit and is not
          insured or guaranteed by the Federal Deposit Insurance Corporation or
          any other government agency.

          The following information provides some indication of the risks of
          investing in the Equity Portfolios by showing how each of the Equity
          Portfolios' performance has varied over time. The Portfolios' Service
          Shares commenced operations on December 31, 1999. The returns shown
          for the Service Shares of these Portfolios reflect the historical
          performance of a different class of shares (the Institutional Shares)
          prior to December 31, 1999, restated based on the Service Shares'
          estimated fees and expenses (ignoring any fee and expense
          limitations). The bar charts depict the change in performance from
          year-to-year during the period indicated but do not include charges
          and expenses attributable to any insurance product which would lower
          the performance illustrated. The Portfolios do not impose any sales or
          other charges that

                                                          Risk return summary  3
<PAGE>

          would affect total return computations. Total return figures include
          the effect of each Portfolio's expenses. The tables compare the
          average annual returns for the Service Shares of each Portfolio for
          the periods indicated to a broad-based securities market index.

           GROWTH PORTFOLIO - SERVICE SHARES

           Annual Returns for Periods Ended 12/31

                             2.71%   29.96%   18.14%   22.49%   35.59%    43.01%
                             1994     1995     1996     1997     1998      1999

           Best Quarter  4th-1998  27.71%  Worst Quarter  3rd-1998 (10.95%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Growth Portfolio                                          43.01%    29.53%         23.86%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                                                                      --------------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

           AGGRESSIVE GROWTH PORTFOLIO - SERVICE SHARES

           Annual Returns for Periods Ended 12/31

                            16.33%   27.38%    7.72%   12.53%   34.19%   123.16%
                             1994     1995     1996     1997     1998      1999

           Best Quarter  4th-1998  58.17%  Worst Quarter  3rd-1998 (15.00%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                         1 year     5 years       (9/13/93)
                <S>                                                      <C>        <C>        <C>
                Aggressive Growth Portfolio                              123.16%    35.83%         33.98%
                S&P MidCap 400 Index*                                     14.72%    23.05%         18.08%
                                                                     ---------------------------------------------
</TABLE>

           * The S&P MidCap 400 Index is an unmanaged group of 400 domestic
             stocks chosen for their market size, liquidity and industry group
             representation.

 4 Janus Aspen Series
<PAGE>

           CAPITAL APPRECIATION PORTFOLIO - SERVICE SHARES

           Annual Returns for Periods Ended 12/31

                            57.91%    64.60%
                             1998      1999

           Best Quarter  4th-1998  40.00%  Worst Quarter  3rd-1998 (9.99%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                           Since Inception
                                                                                 1 year       (5/1/97)
                <S>                                                              <C>       <C>
                Capital Appreciation Portfolio                                   64.60%        56.39%
                S&P 500 Index*                                                   21.03%        27.40%
                                                                             --------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

           BALANCED PORTFOLIO - SERVICE SHARES

           Annual Returns for Periods Ended 12/31

                             0.84%   24.79%   16.18%   21.96%   34.03%    26.03%
                             1994     1995     1996     1997     1998      1999

           Best Quarter  4th-1998  20.26%  Worst Quarter  3rd-1998 (5.02%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Balanced Portfolio                                        26.03%    24.55%         20.51%
                S&P 500 Index*                                            21.03%    28.54%         22.68%
                Lehman Brothers Gov't/Corp Bond Index**                   (2.15%)    7.61%          5.40%
                                                                      --------------------------------------------
</TABLE>

           * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
             a widely recognized, unmanaged index of common stock prices.

          ** Lehman Brothers Gov't/Corp Bond Index is composed of all bonds that
             are of investment grade with at least one year until maturity.

                                                          Risk return summary  5
<PAGE>

           EQUITY INCOME PORTFOLIO - SERVICE SHARES

           Annual Returns for Periods Ended 12/31

                            45.99%    40.39%
                             1998      1999

           Best Quarter  4th-1998  28.47%  Worst Quarter  3rd-1998 (7.23%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                           Since Inception
                                                                                 1 year       (5/1/97)
                <S>                                                              <C>       <C>
                Equity Income Portfolio                                          40.39%        46.19%
                S&P 500 Index*                                                   21.03%        27.40%
                                                                             --------------------------------
</TABLE>

          * The S&P 500 is the Standard & Poor's Composite Index of 500 Stocks,
            a widely recognized, unmanaged index of common stock prices.

           INTERNATIONAL GROWTH PORTFOLIO - SERVICE SHARES

           Annual Returns for Periods Ended 12/31

                            23.15%   34.71%   18.36%   16.88%    79.52%
                             1995     1996     1997     1998      1999

           Best Quarter  4th-1998  56.24%  Worst Quarter  3rd-1998 (17.76%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (5/2/94)
                <S>                                                       <C>       <C>        <C>
                International Growth Portfolio                            79.52%    33.17%         28.19%
                Morgan Stanley Capital International EAFE(R) Index*       26.96%    12.83%         11.22%
                                                                      ----------------------------------------
</TABLE>

           * The Morgan Stanley Capital International EAFE(R) Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 20 Developed Market countries in Europe,
             Australasia and the Far East.

 6 Janus Aspen Series
<PAGE>

           WORLDWIDE GROWTH PORTFOLIO - SERVICE SHARES

           Annual Returns for Periods Ended 12/31

                             1.53%   27.29%   28.80%   21.91%   28.71%    63.49%
                             1994     1995     1996     1997     1998      1999

           Best Quarter  4th-1998  41.62%  Worst Quarter  3rd-1998 (17.00%)


                          Average annual total return for periods ended 12/31/99
                          ------------------------------------------------------

<TABLE>
<CAPTION>
                                                                                               Since Inception
                                                                          1 year    5 years       (9/13/93)
                <S>                                                       <C>       <C>        <C>
                Worldwide Growth Portfolio                                63.49%    33.28%         29.35%
                Morgan Stanley Capital International World Index*         24.93%    19.76%         16.41%
                                                                      --------------------------------------------
</TABLE>

           * The Morgan Stanley Capital International World Index is a market
             capitalization weighted index composed of companies representative
             of the market structure of 21 Developed Market countries in North
             America, Europe and the Asia/Pacific Region.

          The Equity Portfolios' past performance does not necessarily indicate
          how they will perform in the future.

MONEY MARKET PORTFOLIO

          Money Market Portfolio is designed for investors who seek current
          income.

1. WHAT IS THE INVESTMENT OBJECTIVE OF MONEY MARKET PORTFOLIO?

- --------------------------------------------------------------------------------

          - MONEY MARKET PORTFOLIO seeks maximum current income to the extent
            consistent with stability of capital.

          The Trustees may change this objective without a shareholder vote and
          the Portfolio will notify you of any changes that are material. If
          there is a material change in the Portfolio's objective or policies,
          you should consider whether it remains an appropriate investment for
          you. There is no guarantee that the Portfolio will meet its objective.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF MONEY MARKET PORTFOLIO?

          MONEY MARKET PORTFOLIO will invest only in high-quality, short-term
          money market instruments that present minimal credit risks, as
          determined by Janus Capital. The Portfolio invests primarily in high
          quality debt obligations and obligations of financial institutions.
          Debt obligations may include commercial paper, notes and bonds, and
          variable amount master demand notes. Obligations of financial
          institutions include certificates of deposit and time deposits.

                                                          Risk return summary  7
<PAGE>

3. WHAT ARE THE MAIN RISKS OF INVESTING IN MONEY MARKET PORTFOLIO?

          The Portfolio's yields will vary as the short-term securities in the
          portfolio mature and the proceeds are reinvested in securities with
          different interest rates. Over time, the real value of the Portfolio's
          yield may be eroded by inflation. Although Money Market Portfolio
          invests only in high-quality, short-term money market instruments,
          there is a risk that the value of the securities it holds will fall as
          a result of changes in interest rates, an issuer's actual or perceived
          credit-worthiness or an issuer's ability to meet its obligations.

          An investment in Money Market Portfolio is not a deposit of a bank and
          is not insured or guaranteed by the Federal Deposit Insurance
          Corporation or any other government agency. Although the Portfolio
          seeks to preserve the value of your investment at $1.00 per share, it
          is possible to lose money by investing in Money Market Portfolio.

          The following information provides some indication of the risks of
          investing in Money Market Portfolio by showing how Money Market
          Portfolio's performance has varied over time. The Money Market
          Portfolio Service Shares commenced operations on December 31, 1999.
          The returns shown for the Service Shares of this Portfolio reflect the
          historical performance of a different class of shares (the
          Institutional Shares) prior to December 31, 1999, restated based on
          the Service Share's estimated fees and expenses (ignoring any fee and
          expense limitations). The bar chart depicts the change in performance
          from year to year, but does not include charges and expenses
          attributable to any insurance product which would lower the
          performance illustrated. The Portfolio does not impose any sales or
          other charges that would affect total return computations. Total
          return figures include the effect of the Portfolio's expenses.

           MONEY MARKET PORTFOLIO - SERVICE SHARES

           Annual Returns for Periods Ended 12/31

                             4.88%    5.00%    5.03%     4.79%
                             1996     1997     1998      1999

           Best Quarter  4th-1998  1.36%  Worst Quarter  3rd-1998 1.05%


          For the Portfolio's current yield, call the Janus XpressLine(TM) at
          1-888-979-7737.

          Money Market Portfolio's past performance does not necessarily
          indicate how it will perform in the future.

 8 Janus Aspen Series
<PAGE>

FEES AND EXPENSES

          SHAREHOLDER FEES, such as sales loads, redemption fees or exchange
          fees, are charged directly to an investor's account. All Janus funds
          are no-load investments, so you will not pay any shareholder fees when
          you buy or sell shares of the Portfolios. However, each variable
          insurance contract involves fees and expenses not described in this
          prospectus. See the accompanying contract prospectus for information
          regarding contract fees and expenses and any restrictions on purchases
          or allocations.

          ANNUAL FUND OPERATING EXPENSES are paid out of a Portfolio's assets
          and include fees for portfolio management, maintenance of shareholder
          accounts, shareholder servicing, accounting and other services. You do
          not pay these fees directly but, as the example on the next page
          shows, these costs are borne indirectly by all shareholders.

                                                          Risk return summary  9
<PAGE>

          This table and example are designed to assist participants in
          qualified plans that invest in the Shares of the Portfolios in
          understanding the fees and expenses that you may pay as an investor in
          the Shares. OWNERS OF VARIABLE INSURANCE CONTRACTS THAT INVEST IN THE
          SHARES SHOULD REFER TO THE VARIABLE INSURANCE CONTRACT PROSPECTUS FOR
          A DESCRIPTION OF FEES AND EXPENSES, AS THE TABLE AND EXAMPLE DO NOT
          REFLECT DEDUCTIONS AT THE SEPARATE ACCOUNT LEVEL OR CONTRACT LEVEL FOR
          ANY CHARGES THAT MAY BE INCURRED UNDER A CONTRACT.
<TABLE>
<CAPTION>
                                                                                  Total Annual Fund              Total Annual Fund
                                                    Distribution                       Operating                      Operating
                                       Management      (12b-1)        Other            Expenses          Total        Expenses
                                           Fee         Fees(1)       Expenses     Without Waivers(2)    Waivers    With Waivers(2)
    <S>                                <C>          <C>              <C>          <C>                   <C>      <C>
    Growth Portfolio                      0.65%         0.25%         0.02%            0.92%               N/A          0.92%
    Aggressive Growth Portfolio           0.65%         0.25%         0.02%            0.92%               N/A          0.92%
    Capital Appreciation Portfolio        0.65%         0.25%         0.04%            0.94%               N/A          0.94%
    Balanced Portfolio                    0.65%         0.25%         0.02%            0.92%               N/A          0.92%
    Equity Income Portfolio               0.65%         0.25%         0.63%            1.53%              0.03%         1.50%
    International Growth Portfolio        0.65%         0.25%         0.11%            1.01%               N/A          1.01%
    Worldwide Growth Portfolio            0.65%         0.25%         0.05%            0.95%               N/A          0.95%
    Money Market Portfolio                0.25%         0.25%         0.18%            0.68%               N/A          0.68%
</TABLE>

- --------------------------------------------------------------------------------
   (1) Long-term shareholders may pay more than the economic equivalent of
       the maximum front-end sales charges permitted by the National
       Association of Securities Dealers, Inc.

   (2) Expenses are based on the estimated expenses that the new Service
       Shares Class of each Portfolio expects to incur in its initial fiscal
       year. Expenses are stated both with and without contractual waivers by
       Janus Capital. Waivers, if applicable, are first applied against the
       management fee and then against other expenses, and will continue
       until at least the next annual renewal of the advisory agreement. All
       expenses are shown without the effect of any expense offset
       arrangements.
- --------------------------------------------------------------------------------

   EXAMPLE:
   THE FOLLOWING EXAMPLE IS BASED ON EXPENSES WITHOUT WAIVERS (IF ANY).
   This example is intended to help you compare the cost of investing in
   the Portfolios with the cost of investing in other mutual funds. The
   example assumes that you invest $10,000 in each of the Portfolios for
   the time periods indicated then redeem all of your shares at the end of
   those periods. The example also assumes that your investment has a 5%
   return each year, and that the Portfolios' operating expenses remain the
   same. Although your actual costs may be higher or lower, based on these
   assumptions your costs would be:

<TABLE>
<CAPTION>
                                                                  1 Year     3 Years
                                                                  ------------------
    <S>                                                           <C>        <C>
    Growth Portfolio                                               $ 94      $  293
    Aggressive Growth Portfolio                                    $ 94      $  293
    Capital Appreciation Portfolio                                 $ 96      $  300
    Balanced Portfolio                                             $ 94      $  293
    Equity Income Portfolio                                        $156      $  483
    International Growth Portfolio                                 $103      $  322
    Worldwide Growth Portfolio                                     $ 97      $  303
    Money Market Portfolio                                         $ 69      $  218
</TABLE>

 10 Janus Aspen Series
<PAGE>
                                     Investment objectives, principal investment
                                                strategies and risks

          Each of the Portfolios has a similar investment objective and similar
          principal investment strategies to a Janus retail fund:

<TABLE>
                  <S>                                                <C>
                  Growth Portfolio                                                 Janus Fund
                  Aggressive Growth Portfolio                           Janus Enterprise Fund
                  Capital Appreciation Portfolio                            Janus Twenty Fund
                  Balanced Portfolio                                      Janus Balanced Fund
                  Equity Income Portfolio                            Janus Equity Income Fund
                  International Growth Portfolio                          Janus Overseas Fund
                  Worldwide Growth Portfolio                             Janus Worldwide Fund
                  Money Market Portfolio                              Janus Money Market Fund
</TABLE>

          Although it is anticipated that each Portfolio and its corresponding
          retail fund will hold similar securities, differences in asset size,
          cash flow needs and other factors may result in differences in
          investment performance. The expenses of each Portfolio and its
          corresponding retail fund are expected to differ. The variable
          contract owner will also bear various insurance related costs at the
          insurance company level. You should review the accompanying separate
          account prospectus for a summary of fees and expenses.

EQUITY PORTFOLIOS

          This section takes a closer look at the investment objectives of each
          of the Equity Portfolios, their principal investment strategies and
          certain risks of investing in the Equity Portfolios. Strategies and
          policies that are noted as "fundamental" cannot be changed without a
          shareholder vote.

          Please carefully review the "Risks" section of this Prospectus on
          pages 17-18 for a discussion of risks associated with certain
          investment techniques. We've also included a Glossary with
          descriptions of investment terms used throughout this Prospectus.

INVESTMENT OBJECTIVES AND PRINCIPAL INVESTMENT STRATEGIES

DOMESTIC EQUITY PORTFOLIOS

          GROWTH PORTFOLIO
          Growth Portfolio seeks long-term growth of capital in a manner
          consistent with the preservation of capital. It pursues its objective
          by investing primarily in common stocks selected for their growth
          potential. Although the Portfolio can invest in companies of any size,
          it generally invests in larger, more established companies.

          AGGRESSIVE GROWTH PORTFOLIO
          Aggressive Growth Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential, and normally invests at least 50% of its
          equity assets in medium-sized companies. Medium-sized companies are
          those whose market capitalization falls within the range of companies
          in the S&P MidCap 400 Index. Market capitalization is a commonly used
          measure of the size and value of a company. The market capitalizations
          within the Index will vary, but as of December 31, 1999, they ranged
          from approximately $170 million to $37 billion.

            Investment objectives, principal investment strategies and risks  11
<PAGE>

          CAPITAL APPRECIATION PORTFOLIO
          Capital Appreciation Portfolio seeks long-term growth of capital. It
          pursues its objective by investing primarily in common stocks selected
          for their growth potential. The Portfolio may invest in companies of
          any size, from larger, well-established companies to smaller, emerging
          growth companies.

          BALANCED PORTFOLIO
          Balanced Portfolio seeks long-term capital growth, consistent with
          preservation of capital and balanced by current income. It pursues its
          objective by normally investing 40-60% of its assets in securities
          selected primarily for their growth potential and 40-60% of its assets
          in securities selected primarily for their income potential. This
          Portfolio normally invests at least 25% of its assets in fixed-income
          securities.

          EQUITY INCOME PORTFOLIO
          Equity Income Portfolio seeks current income and long-term growth of
          capital. It pursues its objective by normally emphasizing investments
          in common stock, and growth potential is a significant investment
          consideration. The Portfolio tries to provide a lower level of
          volatility than the S&P 500 Index. Normally, it invests at least 65%
          of its assets in income-producing equity securities including common
          and preferred stocks, warrants and securities that are convertible to
          common or preferred stocks.

GLOBAL/INTERNATIONAL EQUITY PORTFOLIOS

          INTERNATIONAL GROWTH PORTFOLIO
          International Growth Portfolio seeks long-term growth of capital.
          Normally, the Portfolio pursues its objective by investing at least
          65% of its total assets in securities of issuers from at least five
          different countries, excluding the United States. Although the
          Portfolio intends to invest substantially all of its assets in issuers
          located outside the United States, it may at times invest in U.S.
          issuers and it may at times invest all of its assets in fewer than
          five countries or even a single country.

          WORLDWIDE GROWTH PORTFOLIO
          Worldwide Growth Portfolio seeks long-term growth of capital in a
          manner consistent with the preservation of capital. It pursues its
          objective by investing primarily in common stocks of companies of any
          size throughout the world. The Portfolio normally invests in issuers
          from at least five different countries, including the United States.
          The Portfolio may at times invest in fewer than five countries or even
          a single country.

 12 Janus Aspen Series
<PAGE>

The following questions and answers are designed to help you better understand
the Equity Portfolios' principal investment strategies.

1. HOW ARE COMMON STOCKS SELECTED?

          Each of the Portfolios may invest substantially all of its assets in
          common stocks if its portfolio manager believes that common stocks
          will appreciate in value. The portfolio managers generally take a
          "bottom up" approach to selecting companies. In other words, they seek
          to identify individual companies with earnings growth potential that
          may not be recognized by the market at large. They make this
          assessment by looking at companies one at a time, regardless of size,
          country of organization, place of principal business activity, or
          other similar selection criteria. Except for Balanced Portfolio and
          Equity Income Portfolio, realization of income is not a significant
          consideration when choosing investments for the Portfolios. Income
          realized on the Portfolios' investments may be incidental to their
          objectives. In the case of Balanced Portfolio and Equity Income
          Portfolio, a portfolio manager may consider dividend-paying
          characteristics to a greater degree in selecting common stock.

2. ARE THE SAME CRITERIA USED TO SELECT FOREIGN SECURITIES?

          Generally, yes. The portfolio managers seek companies that meet their
          selection criteria, regardless of where a company is located. Foreign
          securities are generally selected on a stock-by-stock basis without
          regard to any defined allocation among countries or geographic
          regions. However, certain factors such as expected levels of
          inflation, government policies influencing business conditions, the
          outlook for currency relationships, and prospects for economic growth
          among countries, regions or geographic areas may warrant greater
          consideration in selecting foreign securities. There are no
          limitations on the countries in which the Portfolios may invest and
          the Portfolios may at times have significant foreign exposure.

3. WHAT DOES "MARKET CAPITALIZATION" MEAN?

          Market capitalization is the most commonly used measure of the size
          and value of a company. It is computed by multiplying the current
          market price of a share of the company's stock by the total number of
          its shares outstanding. As noted previously, market capitalization is
          an important investment criteria for Aggressive Growth Portfolio.
          Although the other Equity Portfolios offered by this Prospectus do not
          emphasize companies of any particular size, Portfolios with a larger
          asset base are more likely to invest in larger, more established
          issuers.

4. HOW DO BALANCED PORTFOLIO AND EQUITY INCOME PORTFOLIO DIFFER FROM EACH OTHER?

          Although Equity Income Portfolio invests substantially all of its
          assets in common stocks, it emphasizes investments in dividend-paying
          common stocks and other equity securities characterized by relatively
          greater price stability. Balanced Portfolio places a greater emphasis
          on the income component of its portfolio and invests to a greater
          degree in securities selected primarily for their income potential. As
          a result it is expected to be less volatile than Equity Income
          Portfolio.

5. HOW DOES EQUITY INCOME PORTFOLIO TRY TO LIMIT PORTFOLIO VOLATILITY?

          Equity Income Portfolio seeks to provide a lower level of volatility
          than the stock market at large, as measured by the S&P 500. The lower
          volatility sought by this Portfolio is expected to result primarily
          from investments in dividend-paying common stocks and other equity
          securities characterized by relatively greater price stability. The
          greater price stability sought by Equity Income Portfolio may be
          characteristic of companies that generate above average free cash
          flows. A company may use free cash flows for a number of purposes
          including commencing or increasing dividend payments, repurchasing its
          own stock or retiring

            Investment objectives, principal investment strategies and risks  13
<PAGE>

          outstanding debt. The portfolio manager also considers growth
          potential in selecting this Portfolio's securities and may hold
          securities selected solely for their growth potential.

6. HOW ARE ASSETS ALLOCATED BETWEEN THE GROWTH AND INCOME COMPONENTS OF BALANCED
   PORTFOLIO'S HOLDINGS?

          Balanced Portfolio shifts assets between the growth and income
          components of its holdings based on the portfolio manager's analysis
          of relevant market, financial and economic conditions. If the
          portfolio manager believes that growth securities will provide better
          returns than the yields then available or expected on income-producing
          securities, the Portfolio will place a greater emphasis on the growth
          component.

7. WHAT TYPES OF SECURITIES MAKE UP THE GROWTH COMPONENT OF THE BALANCED
   PORTFOLIO AND EQUITY INCOME PORTFOLIOS?

          The growth component of these Portfolios is expected to consist
          primarily of common stocks, but may also include warrants, preferred
          stocks or convertible securities selected primarily for their growth
          potential.

8. WHAT TYPES OF SECURITIES MAKE UP THE INCOME COMPONENT OF BALANCED PORTFOLIO'S
   HOLDINGS?

          The income component of Balanced Portfolio is expected to consist of
          securities that the portfolio manager believes have income potential.
          Such securities may include equity securities, convertible securities
          and all types of debt securities. Equity securities may be included in
          the income component of the Portfolio if they currently pay dividends
          or the portfolio manager believes they have the potential for either
          increasing their dividends or commencing dividends, if none are
          currently paid.

 14 Janus Aspen Series
<PAGE>

GENERAL PORTFOLIO POLICIES OF THE PORTFOLIOS OTHER THAN MONEY MARKET PORTFOLIO

          Unless otherwise stated, each of the following policies applies to all
          of the Portfolios other than Money Market Portfolio. The percentage
          limitations included in these policies and elsewhere in this
          Prospectus apply at the time of purchase of the security. So, for
          example, if a Portfolio exceeds a limit as a result of market
          fluctuations or the sale of other securities, it will not be required
          to dispose of any securities.

          CASH POSITION
          When a portfolio manager believes that market conditions are
          unfavorable for profitable investing, or when he or she is otherwise
          unable to locate attractive investment opportunities, the Portfolios'
          cash or similar investments may increase. In other words, the
          Portfolios do not always stay fully invested in stocks and bonds. Cash
          or similar investments generally are a residual - they represent the
          assets that remain after a portfolio manager has committed available
          assets to desirable investment opportunities. However, a portfolio
          manager may also temporarily increase a Portfolio's cash position to
          protect its assets or maintain liquidity. Partly because the portfolio
          managers act independently of each other, the cash positions of the
          Portfolios may vary significantly.

          When a Portfolio's investments in cash or similar investments
          increase, it may not participate in market advances or declines to the
          same extent that it would if the Portfolio remained more fully
          invested in stocks or bonds.

          OTHER TYPES OF INVESTMENTS
          The Equity Portfolios invest primarily in domestic and foreign equity
          securities, which may include preferred stocks, common stocks,
          warrants and securities convertible into common or preferred stocks.
          The Equity Portfolios also invest in domestic and foreign equity
          securities with varying degrees of emphasis on income. The Portfolios
          may also invest to a lesser degree in other types of securities. These
          securities (which are described in the Glossary) may include:

          - debt securities

          - indexed/structured securities

          - high-yield/high-risk bonds (less than 35% of each Portfolio's
            assets)

          - options, futures, forwards, swaps and other types of derivatives for
            hedging purposes or for non-hedging purposes such as seeking to
            enhance return

          - securities purchased on a when-issued, delayed delivery or forward
            commitment basis

          ILLIQUID INVESTMENTS
          Each Portfolio may invest up to 15% of its net assets in illiquid
          investments. An illiquid investment is a security or other position
          that cannot be disposed of quickly in the normal course of business.
          For example, some securities are not registered under U.S. securities
          laws and cannot be sold to the U.S. public because of SEC regulations
          (these are known as "restricted securities"). Under procedures adopted
          by the Portfolios' Trustees, certain restricted securities may be
          deemed liquid, and will not be counted toward this 15% limit.

          FOREIGN SECURITIES
          The Portfolios may invest without limit in foreign equity and debt
          securities. The Portfolios may invest directly in foreign securities
          denominated in a foreign currency and not publicly traded in the
          United

            Investment objectives, principal investment strategies and risks  15
<PAGE>

          States. Other ways of investing in foreign securities include
          depositary receipts or shares, and passive foreign investment
          companies.

          SPECIAL SITUATIONS
          Each Portfolio may invest in special situations. A special situation
          arises when, in the opinion of a Portfolio's manager, the securities
          of a particular issuer will be recognized and appreciate in value due
          to a specific development with respect to that issuer. Developments
          creating a special situation might include, among others, a new
          product or process, a technological breakthrough, a management change
          or other extraordinary corporate event, or differences in market
          supply of and demand for the security. A Portfolio's performance could
          suffer if the anticipated development in a "special situation"
          investment does not occur or does not attract the expected attention.

          PORTFOLIO TURNOVER
          The Portfolios generally intend to purchase securities for long-term
          investment although, to a limited extent, a Portfolio may purchase
          securities in anticipation of relatively short-term price gains.
          Short-term transactions may also result from liquidity needs,
          securities having reached a price or yield objective, changes in
          interest rates or the credit standing of an issuer, or by reason of
          economic or other developments not foreseen at the time of the
          investment decision. A Portfolio may also sell one security and
          simultaneously purchase the same or a comparable security to take
          advantage of short-term differentials in bond yields or securities
          prices. Changes are made in a Portfolio's holdings whenever its
          portfolio manager believes such changes are desirable. Portfolio
          turnover rates are generally not a factor in making buy and sell
          decisions.

          Increased portfolio turnover may result in higher costs for brokerage
          commissions, dealer mark-ups and other transaction costs and may also
          result in taxable capital gains. Higher costs associated with
          increased portfolio turnover may offset gains in a Portfolio's
          performance.

 16 Janus Aspen Series
<PAGE>

RISKS FOR EQUITY PORTFOLIOS

          Because the Portfolios may invest substantially all of their assets in
          common stocks, the main risk is the risk that the value of the stocks
          they hold might decrease in response to the activities of an
          individual company or in response to general market and/or economic
          conditions. If this occurs, a Portfolio's share price may also
          decrease. A Portfolio's performance may also be affected by risks
          specific to certain types of investments, such as foreign securities,
          derivative investments, non-investment grade debt securities, initial
          public offerings (IPOs) or companies with relatively small market
          capitalizations. IPOs and other investment techniques may have a
          magnified performance impact on a portfolio with a small asset base. A
          portfolio may not experience similar performance as its assets grow.

The following questions and answers are designed to help you better understand
some of the risks of investing in the Equity Portfolios.

1. THE PORTFOLIOS MAY INVEST IN SMALLER OR NEWER COMPANIES. DOES THIS CREATE ANY
   SPECIAL RISKS?

          Many attractive investment opportunities may be smaller, start-up
          companies offering emerging products or services. Smaller or newer
          companies may suffer more significant losses as well as realize more
          substantial growth than larger or more established issuers because
          they may lack depth of management, be unable to generate funds
          necessary for growth or potential development, or be developing or
          marketing new products or services for which markets are not yet
          established and may never become established. In addition, such
          companies may be insignificant factors in their industries and may
          become subject to intense competition from larger or more established
          companies. Securities of smaller or newer companies may have more
          limited trading markets than the markets for securities of larger or
          more established issuers, and may be subject to wide price
          fluctuations. Investments in such companies tend to be more volatile
          and somewhat more speculative.

2. HOW DOES THE NONDIVERSIFIED STATUS OF AGGRESSIVE GROWTH PORTFOLIO AND CAPITAL
   APPRECIATION PORTFOLIO AFFECT THEIR RISK?

          Diversification is a way to reduce risk by investing in a broad range
          of stocks or other securities. A "nondiversified" portfolio has the
          ability to take larger positions in a smaller number of issuers.
          Because the appreciation or depreciation of a single stock may have a
          greater impact on the NAV of a nondiversified portfolio, its share
          price can be expected to fluctuate more than a comparable diversified
          portfolio. This fluctuation, if significant, may affect the
          performance of a Portfolio.

3. HOW COULD THE PORTFOLIOS' INVESTMENTS IN FOREIGN SECURITIES AFFECT THEIR
   PERFORMANCE?

          The Portfolios may invest without limit in foreign securities either
          indirectly (e.g., depositary receipts) or directly in foreign markets.
          Investments in foreign securities, including those of foreign
          governments, may involve greater risks than investing in domestic
          securities because the Portfolios' performance may depend on issues
          other than the performance of a particular company. These issues
          include:

          - CURRENCY RISK. As long as a Portfolio holds a foreign security, its
            value will be affected by the value of the local currency relative
            to the U.S. dollar. When a Portfolio sells a foreign denominated
            security, its value may be worth less in U.S. dollars even if the
            security increases in value in its home country. U.S. dollar
            denominated securities of foreign issuers may also be affected by
            currency risk.

          - POLITICAL AND ECONOMIC RISK. Foreign investments may be subject to
            heightened political and economic risks, particularly in emerging
            markets which may have relatively unstable governments, immature
            economic structures, national policies restricting investments by
            foreigners, different legal systems, and economies based on only a
            few industries. In some countries, there is the risk that the
            government may

            Investment objectives, principal investment strategies and risks  17
<PAGE>

            take over the assets or operations of a company or that the
            government may impose taxes or limits on the removal of a
            Portfolio's assets from that country.

          - REGULATORY RISK. There may be less government supervision of foreign
            markets. As a result, foreign issuers may not be subject to the
            uniform accounting, auditing and financial reporting standards and
            practices applicable to domestic issuers and there may be less
            publicly available information about foreign issuers.

          - MARKET RISK. Foreign securities markets, particularly those of
            emerging market countries, may be less liquid and more volatile than
            domestic markets. Certain markets may require payment for securities
            before delivery and delays may be encountered in settling securities
            transactions. In some foreign markets, there may not be protection
            against failure by other parties to complete transactions.

          - TRANSACTION COSTS. Costs of buying, selling and holding foreign
            securities, including brokerage, tax and custody costs, may be
            higher than those involved in domestic transactions.

4. ARE THERE SPECIAL RISKS ASSOCIATED WITH INVESTMENTS IN HIGH-YIELD/HIGH-RISK
   BONDS?

          High-yield/high-risk bonds (or "junk" bonds) are bonds rated below
          investment grade by the primary rating agencies such as Standard &
          Poor's and Moody's. The value of lower quality bonds generally is more
          dependent on credit risk, or the ability of the issuer to meet
          interest and principal payments, than investment grade debt bonds.
          Issuers of high-yield bonds may not be as strong financially as those
          issuing bonds with higher credit ratings and are more vulnerable to
          real or perceived economic changes, political changes or adverse
          developments specific to the issuer.

          Please refer to the SAI for a description of bond rating categories.

5. HOW DO THE PORTFOLIOS TRY TO REDUCE RISK?

          The Portfolios may use futures, options, swaps and other derivative
          instruments to "hedge" or protect their portfolios from adverse
          movements in securities prices and interest rates. The Portfolios may
          also use a variety of currency hedging techniques, including forward
          currency contracts, to manage exchange rate risk. The portfolio
          managers believe the use of these instruments will benefit the
          Portfolios. However, a Portfolio's performance could be worse than if
          the Portfolio had not used such instruments if a portfolio manager's
          judgement proves incorrect. Risks associated with the use of
          derivative instruments are described in the SAI.

 18 Janus Aspen Series
<PAGE>

MONEY MARKET PORTFOLIO

          This section takes a closer look at the investment objective of Money
          Market Portfolio, its principal investment strategies and certain
          risks of investing in the Portfolio. Strategies and policies that are
          noted as "fundamental" cannot be changed without a shareholder vote.

          Money Market Portfolio is subject to certain specific SEC rule
          requirements. Among other things, the Portfolio is limited to
          investing in U.S. dollar-denominated instruments with a remaining
          maturity of 397 days or less (as calculated pursuant to Rule 2a-7
          under the 1940 Act).

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

          Money Market Portfolio seeks maximum current income to the extent
          consistent with stability of capital. It pursues its objective by
          investing primarily in high quality debt obligations and obligations
          of financial institutions. Debt obligations may include commercial
          paper, notes and bonds, and variable amount master demand notes.
          Obligations of financial institutions include certificates of deposit
          and time deposits.

          Money Market Portfolio will:

          - invest in high quality, short-term money market instruments that
            present minimal credit risks, as determined by Janus Capital

          - invest only in U.S. dollar-denominated instruments that have a
            remaining maturity of 397 days or less (as calculated pursuant to
            Rule 2a-7 under the 1940 Act)

          - maintain a dollar-weighted average portfolio maturity of 90 days or
            less

TYPES OF INVESTMENTS

          Money Market Portfolio invests primarily in:

          - high quality debt obligations

          - obligations of financial institutions

          The Portfolio may also invest (to a lesser degree) in:

          - U.S. Government Securities (securities issued or guaranteed by the
            U.S. government, its agencies and instrumentalities)

          - municipal securities

          DEBT OBLIGATIONS

          The Portfolio may invest in U.S. dollar denominated debt obligations.
          Debt obligations include:

          - commercial paper

          - notes and bonds

          - variable amount master demand notes (the payment obligations on
            these instruments may be backed by securities, swap agreements or
            other assets, by a guarantee of a third party or solely by the
            unsecured promise of the issuer to make payments when due)

          - privately issued commercial paper or other securities that are
            restricted as to disposition under the federal securities laws

            Investment objectives, principal investment strategies and risks  19
<PAGE>

          OBLIGATIONS OF FINANCIAL INSTITUTIONS

          Examples of obligations of financial institutions include:

          - negotiable certificates of deposit, bankers' acceptances, time
            deposits and other obligations of U.S. banks (including savings and
            loan associations) having total assets in excess of one billion
            dollars and U.S. branches of foreign banks having total assets in
            excess of ten billion dollars

          - Eurodollar and Yankee bank obligations (Eurodollar bank obligations
            are dollar-denominated certificates of deposit or time deposits
            issued outside the U.S. capital markets by foreign branches of U.S.
            banks and by foreign banks. Yankee bank obligations are
            dollar-denominated obligations issued in the U.S. capital markets by
            foreign banks)

          - other U.S. dollar-denominated obligations of foreign banks having
            total assets in excess of ten billion dollars that Janus Capital
            believes are of an investment quality comparable to obligations of
            U.S. banks in which the Portfolio may invest

          Foreign, Eurodollar (and to a limited extent, Yankee) bank obligations
          are subject to certain sovereign risks. One such risk is the
          possibility that a foreign government might prevent dollar-denominated
          funds from flowing across its borders. Other risks include: adverse
          political and economic developments in a foreign country; the extent
          and quality of government regulation of financial markets and
          institutions; the imposition of foreign withholding taxes; and
          expropriation or nationalization of foreign issuers.

INVESTMENT TECHNIQUES

          The following is a description of other investment techniques that
          Money Market Portfolio may use:

          PARTICIPATION INTERESTS
          A participation interest gives Money Market Portfolio a proportionate,
          undivided interest in underlying debt securities and sometimes carries
          a demand feature.

          DEMAND FEATURES
          Demand features give Money Market Portfolio the right to resell
          securities at specified periods prior to their maturity dates. Demand
          features may shorten the life of a variable or floating rate security,
          enhance the instrument's credit quality and provide a source of
          liquidity.

          Demand features are often issued by third party financial
          institutions, generally domestic and foreign banks. Accordingly, the
          credit quality and liquidity of Money Market Portfolio's investments
          may be dependent in part on the credit quality of the banks supporting
          Money Market Portfolio's investments. This will result in exposure to
          risks pertaining to the banking industry, including the foreign
          banking industry. Brokerage firms and insurance companies also provide
          certain liquidity and credit support.

          VARIABLE AND FLOATING RATE SECURITIES
          Money Market Portfolio may invest in securities which have variable or
          floating rates of interest. These securities pay interest at rates
          that are adjusted periodically according to a specified formula,
          usually with reference to an interest rate index or market interest
          rate. Variable and floating rate securities are subject to changes in
          value based on changes in market interest rates or changes in the
          issuer's or guarantor's creditworthiness.

 20 Janus Aspen Series
<PAGE>

          MORTGAGE- AND ASSET-BACKED SECURITIES
          Money Market Portfolio may purchase fixed or variable rate
          mortgage-backed securities issued by the Government National Mortgage
          Association, Federal National Mortgage Association, the Federal Home
          Loan Mortgage Corporation, or other governmental or government-related
          entity. The Portfolio may purchase other mortgage- and asset-backed
          securities including securities backed by automobile loans, equipment
          leases or credit card receivables.

          Unlike traditional debt instruments, payments on these securities
          include both interest and a partial payment of principal. Prepayments
          of the principal of underlying loans may shorten the effective
          maturities of these securities and may result in the Portfolio having
          to reinvest proceeds at a lower interest rate.

          REPURCHASE AGREEMENTS
          Money Market Portfolio may enter into collateralized repurchase
          agreements. Repurchase agreements are transactions in which the
          Portfolio purchases securities and simultaneously commits to resell
          those securities to the seller at an agreed-upon price on an
          agreed-upon future date. The repurchase price reflects a market rate
          of interest and is collateralized by cash or securities.

          If the seller of the securities underlying a repurchase agreement
          fails to pay the agreed resale price on the agreed delivery date,
          Money Market Portfolio may incur costs in disposing of the collateral
          and may experience losses if there is any delay in its ability to do
          so.

            Investment objectives, principal investment strategies and risks  21
<PAGE>
Management of the portfolios

INVESTMENT ADVISER

          Janus Capital, 100 Fillmore Street, Denver, Colorado 80206-4928, is
          the investment adviser to each of the Portfolios and is responsible
          for the day-to-day management of the investment portfolios and other
          business affairs of the Portfolios.

          Janus Capital began serving as investment adviser to Janus Fund in
          1970 and currently serves as investment adviser to all of the Janus
          retail funds, acts as sub-adviser for a number of private-label mutual
          funds and provides separate account advisory services for
          institutional accounts.

          Janus Capital furnishes continuous advice and recommendations
          concerning each Portfolio's investments. Janus Capital also furnishes
          certain administrative, compliance and accounting services for the
          Portfolios, and may be reimbursed by the Portfolios for its costs in
          providing those services. In addition, Janus Capital employees serve
          as officers of the Trust and Janus Capital provides office space for
          the Portfolios and pays the salaries, fees and expenses of all
          Portfolio officers and those Trustees who are affiliated with Janus
          Capital.

          Participating insurance companies that purchase the Portfolios' Shares
          may perform certain administrative services relating to the Portfolios
          and Janus Capital or the Portfolios may pay those companies for such
          services.

MANAGEMENT EXPENSES AND EXPENSE LIMITS

          Each Portfolio pays Janus Capital a management fee which is calculated
          daily and paid monthly. The advisory agreement with each Portfolio
          spells out the management fee and other expenses that the Portfolios
          must pay. Each of the Portfolios is subject to the following
          management fee schedule (expressed as an annual rate). In addition,
          the Shares of each Portfolio incur expenses not assumed by Janus
          Capital, including the distribution fee, transfer agent and custodian
          fees and expenses, legal and auditing fees, printing and mailing costs
          of sending reports and other information to existing shareholders, and
          independent Trustees' fees and expenses.

<TABLE>
<CAPTION>
                                                           Average Daily
                                                             Net Assets        Annual Rate         Expense Limit
     Fee Schedule                                           of Portfolio      Percentage (%)       Percentage (%)
- -------------------------------------------------------------------------------------------------------------------
<S>                                                       <C>                 <C>               <C>
     Growth Portfolio                                     All Asset Levels         0.65                 N/A
     Aggressive Growth Portfolio
     Capital Appreciation Portfolio
     Balanced Portfolio
     International Growth Portfolio
     Worldwide Growth Portfolio
- -------------------------------------------------------------------------------------------------------------------
     Equity Income Portfolio                              All Asset Levels         0.65              1.25(1)
- -------------------------------------------------------------------------------------------------------------------
     Money Market Portfolio                               All Asset Levels         0.25              0.50(2)
- -------------------------------------------------------------------------------------------------------------------
</TABLE>

(1) Janus Capital has agreed to limit the Portfolio's expenses as indicated
    until at least the next annual renewal of the advisory agreement. The
    distribution fee described on page 27 is not included in the expense limit.
(2) Janus Capital has agreed to limit the Portfolio's expenses as indicated
    until at least the next annual renewal of the advisory agreements. The
    distribution fee described on page 27 is not included in the expense limit.
    As noted in the fee table on page 10, however, the Portfolio's expenses
    without waivers are not expected to exceed the expense limit.

 22 Janus Aspen Series
<PAGE>

          For the fiscal year ended December 31, 1999, each Portfolio paid Janus
          Capital the following management fees based upon each Portfolio's
          average net assets: 0.67% for Growth Portfolio, 0.68% for Aggressive
          Growth Portfolio, 0.75% for Capital Appreciation Portfolio, 0.67% for
          Balanced Portfolio, 0.75% for Equity Income Portfolio, 0.73% for
          International Growth Portfolio, 0.66% for Worldwide Growth Portfolio
          and 0.25% for Money Market Portfolio. These rates were based on a
          higher fee rate that was previously in effect for certain of these
          Portfolios.

INVESTMENT PERSONNEL

PORTFOLIO MANAGERS

LAURENCE J. CHANG
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio which he has
            co-managed since May 1998 and December 1999, respectively. He has
            also co-managed Janus Overseas Fund and Janus Worldwide Fund
            since April 1998 and September 1999, respectively. He served as
            assistant portfolio manager for these funds since 1996. Mr. Chang
            joined Janus Capital in 1993 as a research analyst. He received
            an undergraduate degree with honors in Religion with a
            concentration in Philosophy from Dartmouth College and a Masters
            Degree in Political Science from Stanford University. He has
            earned the right to use the Chartered Financial Analyst
            designation.

JAMES P. GOFF
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Aggressive
            Growth Portfolio, which he has managed since inception. Mr. Goff
            joined Janus Capital in 1988 and has managed Janus Enterprise
            Fund since its inception. Mr. Goff co-managed or managed Janus
            Venture Fund from December 1993 to February 1997. He holds a
            Bachelor of Arts in Economics from Yale University and he has
            earned the right to use the Chartered Financial Analyst
            designation.

HELEN YOUNG HAYES
- --------------------------------------------------------------------------------
            is Executive Vice President and co-manager of International
            Growth Portfolio and Worldwide Growth Portfolio, which she has
            managed or co-managed since inception. Ms. Hayes joined Janus
            Capital in 1987 and has managed or co-managed Janus Worldwide
            Fund and Janus Overseas Fund since their inceptions. She holds a
            Bachelor of Arts in Economics from Yale University and she has
            earned the right to use the Chartered Financial Analyst
            designation.

SHARON S. PICHLER
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Money Market
            Portfolio, which she has managed since inception. She also has
            managed Janus Money Market Fund, Janus Government Money Market
            Fund and Janus Tax-Exempt Money Market Fund since inception. She
            holds a Bachelor of Arts in Economics from Michigan State
            University and a Master of Business Administration from the
            University of Texas at San Antonio. Ms. Pichler has earned the
            right to use the Chartered Financial Analyst designation.

                                                Management of the portfolios  23
<PAGE>

KAREN L. REIDY
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Balanced
            Portfolio and Equity Income Portfolio as of January 2000, and an
            assistant portfolio manager of Growth Portfolio since 1998. She
            also manages Janus Balanced Fund and Janus Equity Income Fund as
            of January 2000. She is also assistant portfolio manager of Janus
            Fund. Prior to joining Janus Capital in 1995, she worked for
            Price Waterhouse as a manager in both the Mergers and
            Acquisitions and Audit business units. In this capacity, Ms.
            Reidy performed due diligence work for corporate clients and
            oversaw audit engagements. She received an undergraduate degree
            in Accounting from the University of Colorado in 1989 and passed
            the CPA exam in 1992. She has earned the right to use the
            Chartered Financial Analyst designation.

BLAINE P. ROLLINS
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Growth
            Portfolio as of January 2000. He previously managed Balanced
            Portfolio from May 1996 to December 1999 and Equity Income
            Portfolio from its inception to December 1999. Mr. Rollins joined
            Janus Capital in 1990 and has managed Janus Fund since January
            2000, Janus Balanced Fund from January 1996 until December 1999
            and Janus Equity Income Fund from inception until December 1999.
            He was an assistant portfolio manager of Janus Fund from January
            1994 until December 1999. He gained experience as a fixed-income
            trader and equity research analyst prior to managing Balanced
            Portfolio. He holds a Bachelor of Science in Finance from the
            University of Colorado and he has earned the right to use the
            Chartered Financial Analyst designation.

SCOTT W. SCHOELZEL
- --------------------------------------------------------------------------------
            is Executive Vice President and portfolio manager of Capital
            Appreciation Portfolio, which he has managed since its inception.
            He is portfolio manager of Janus Twenty Fund, which he has
            managed since August 1997. He previously managed Janus Olympus
            Fund from its inception to August 1997. Mr. Schoelzel joined
            Janus Capital in January 1994. He holds a Bachelor of Arts in
            Business from Colorado College.

ASSISTANT PORTFOLIO MANAGERS

MATTHEW A. ANKRUM
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            He is also assistant portfolio manager of Janus Enterprise Fund.
            Mr. Ankrum joined Janus Capital as an intern in June 1996, and
            became an equity research analyst in August 1997. Prior to
            joining Janus, Mr. Ankrum worked as a corporate finance analyst
            at William Blair and Company from 1993 through 1995. He was also
            a fixed-income research analyst at Conseco Capital Management.
            Mr. Ankrum has an undergraduate degree in Business Administration
            from the University of Wisconsin and a Master of Business
            Administration from the University of Chicago. Mr. Ankrum has
            earned the right to use the Chartered Financial Analyst
            designation.

 24 Janus Aspen Series
<PAGE>

DAVID C. DECKER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. He is also
            an assistant portfolio manager of Janus Fund. He is Executive
            Vice President and portfolio manager of Strategic Value
            Portfolio, Janus Strategic Value Fund and Janus Special
            Situations Fund, each of which he has managed since its
            inception. He obtained a Masters of Business Administration in
            Finance from the Fuqua School of Business at Duke University and
            a Bachelor of Arts in Economics and Political Science from Tufts
            University. Mr. Decker has earned the right to use the Chartered
            Financial Analyst designation.

RON SACHS
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Aggressive Growth Portfolio.
            Mr. Sachs joined Janus Capital in 1996 as a research analyst.
            Prior to coming to Janus, he worked as a consultant for Bain &
            Company and as an attorney for Willkie, Farr & Gallagher. Mr.
            Sachs graduated from Princeton cum laude with an undergraduate
            degree in economics. He obtained his law degree from the
            University of Michigan. Mr. Sachs has earned the right to use the
            Chartered Financial Analyst designation.

DANIEL D. SCHOEN
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Money Market Portfolio. He
            joined Janus in July 1993 and has worked as a trader and credit
            analyst on Janus Money Market Funds. He holds a Bachelor of Arts
            in Economics from the University of Colorado.

JOHN H. SCHREIBER
- --------------------------------------------------------------------------------
            is an assistant portfolio manager of Growth Portfolio. Mr.
            Schreiber joined Janus Capital in 1997 as an equity research
            analyst. Prior to coming to Janus he was an equity analyst with
            Fidelity Investments. Mr. Schreiber holds a Bachelor of Science
            degree in mechanical engineering from the University of
            Washington and an MBA from Harvard University.

                                                Management of the portfolios  25
<PAGE>
Other information

          CLASSES OF SHARES

          Each Portfolio currently offers two or three classes of shares, one of
          which, the Service Shares, are offered pursuant to this prospectus.
          The Shares offered by this prospectus are available only in connection
          with investment in and payments under variable insurance contracts as
          well as certain qualified retirement plans that require a fee from
          Portfolio assets to procure distribution and administrative services
          to contract owners and plan participants. Institutional Shares of each
          Portfolio are available only in connection with investment in and
          payments under variable insurance contracts, as well as certain
          qualified retirement plans. Retirement Shares of certain Portfolios
          are offered only to qualified plans using plan service providers that
          are compensated for providing distribution and/or record keeping and
          other administrative services provided to plan participants. Because
          the expenses of each class may differ, the performance of each class
          is expected to differ. If you would like additional information about
          either the Institutional Shares or the Retirement Shares, please call
          1-800-525-0020.

          During the third quarter of 2000, the Retirement Shares shareholders
          will be asked to approve the spin-off of the Retirement Shares into a
          separate Delaware business trust, Janus Adviser Series. In connection
          with this spin-off, each Portfolio will distribute all of its ordinary
          income and capital gain income earned through the date of the
          spin-off. The distributions will be made for all classes, including
          Service Shares. It is anticipated that the spin-off and distributions
          will occur during the third quarter of 2000.

          DISTRIBUTION FEE

          Under a distribution and service plan adopted in accordance with Rule
          12b-1 under the 1940 Act, the Shares may pay Janus Distributors, Inc.,
          the Trust's distributor, a fee at an annual rate of up to 0.25% of the
          average daily net assets of the Shares of a Portfolio. Under the terms
          of the Plan, the Trust is authorized to make payments to Janus
          Distributors for remittance to insurance companies and qualified plan
          service providers as compensation for distribution and shareholder
          servicing performed by such entities. Because 12b-1 fees are paid out
          of the Service Shares' assets on an ongoing basis, they will increase
          the cost of your investment and may cost you more than paying other
          types of sales charges.

          CONFLICTS OF INTEREST

          The Trust's shares are available only to variable annuity and variable
          life separate accounts of insurance companies that are unaffiliated
          with Janus Capital and to certain qualified retirement plans. Although
          the Portfolios do not currently anticipate any disadvantages to owners
          of variable insurance contracts because each Portfolio offers its
          shares to such entities, there is a possibility that a material
          conflict may arise. The Trustees monitor events in order to identify
          any disadvantages or material irreconcilable conflicts and to
          determine what action, if any, should be taken in response. If a
          material disadvantage or conflict occurs, the Trustees may require one
          or more insurance company separate accounts or qualified plans to
          withdraw its investments in one or more Portfolios or substitute
          Shares of another Portfolio. If this occurs, a Portfolio may be forced
          to sell its securities at disadvantageous prices. In addition, the
          Trustees may refuse to sell Shares of any Portfolio to any separate
          account or qualified plan or may suspend or terminate the offering of
          a Portfolio's Shares if such action is required by law or regulatory
          authority or is in the best interests of that Portfolio's
          shareholders. It is possible that a qualified plan investing in the
          Portfolios could lose its qualified plan status under the Internal
          Revenue Code, which could have adverse tax consequences on insurance
          company separate accounts investing in the Shares. Janus Capital
          intends to monitor such qualified plans and the Portfolios may
          discontinue sales to a qualified plan and require plan participants
          with existing investments in the Shares to redeem those investments if
          a plan loses (or in the opinion of Janus Capital is at risk of losing)
          its qualified plan status.

 26 Janus Aspen Series
<PAGE>

          DISTRIBUTION OF EACH PORTFOLIO

          Each Portfolio is distributed by Janus Distributors, Inc., a member of
          the National Association of Securities Dealers, Inc. ("NASD"). To
          obtain information about NASD member firms and their associated
          persons, you may contact NASD Regulation, Inc. at www.nasdr.com, or
          the Public Disclosure Hotline at 800-289-9999. An investor brochure
          containing information describing the Public Disclosure Program is
          available from NASD Regulation, Inc.

                                                           Other information  27
<PAGE>
Distributions and taxes

DISTRIBUTIONS

          To avoid taxation of the Portfolios, the Internal Revenue Code
          requires each Portfolio to distribute net income and any net gains
          realized on its investments annually. A Portfolio's income from
          dividends and interest and any net realized short-term gains are paid
          to shareholders as ordinary income dividends. Net realized long-term
          gains are paid to shareholders as capital gains distributions.

PORTFOLIOS OTHER THAN MONEY MARKET PORTFOLIO

          Each class of each Portfolio, other than Money Market Portfolio,
          distributes substantially all of its investment income at least
          semi-annually and its net realized gains, if any, at least annually.
          All dividends and capital gains distributions from Shares of a
          Portfolio will automatically be reinvested into additional Shares of
          that Portfolio.

          HOW DISTRIBUTIONS AFFECT NAV

          Distributions, other than daily income dividends, are paid to
          shareholders as of the record date of the distribution of a Portfolio,
          regardless of how long the shares have been held. Undistributed income
          and realized gains are included in the daily NAV of a Portfolio's
          Shares. The Share price of a Portfolio drops by the amount of the
          distribution, net of any subsequent market fluctuations. For example,
          assume that on December 31, the Shares of Growth Portfolio declared a
          dividend in the amount of $0.25 per share. If the price of Growth
          Portfolio's Shares was $10.00 on December 30, the share price on
          December 31 would be $9.75, barring market fluctuations.

MONEY MARKET PORTFOLIO

          For the Shares of Money Market Portfolio, dividends representing
          substantially all of the net investment income and any net realized
          gains on sales of securities are declared daily, Saturdays, Sundays
          and holidays included, and distributed on the last business day of
          each month. If a month begins on a Saturday, Sunday or holiday,
          dividends for those days are declared at the end of the preceding
          month and distributed on the first business day of the month. All
          distributions will be automatically reinvested in Shares of the
          Portfolio.

TAXES

          TAXES ON DISTRIBUTIONS

          Because Shares of the Portfolios may be purchased only through
          variable insurance contracts and qualified plans, it is anticipated
          that any income dividends or capital gains distributions made by the
          Shares of a Portfolio will be exempt from current taxation if left to
          accumulate within the variable insurance contract or qualified plan.
          Generally, withdrawals from such contracts or plans may be subject to
          ordinary income tax and, if made before age 59 1/2, a 10% penalty tax.
          The tax status of your investment depends on the features of your
          qualified plan or variable insurance contract. Further information may
          be found in your plan documents or in the prospectus of the separate
          account offering such contract.

          TAXATION OF THE PORTFOLIOS

          Dividends, interest and some gains received by the Portfolios on
          foreign securities may be subject to tax withholding or other foreign
          taxes. The Portfolios may from year to year make the election
          permitted under Section 853 of the Internal Revenue Code to pass
          through such taxes to shareholders as a foreign tax credit. If such
          election is not made, any foreign taxes paid or accrued will represent
          an expense to the Portfolios which will reduce their investment
          income.

 28 Janus Aspen Series
<PAGE>

          The Portfolios do not expect to pay any federal income or excise taxes
          because they intend to meet certain requirements of the Internal
          Revenue Code. In addition, because a class of shares of each Portfolio
          are sold in connection with variable insurance contracts, each
          Portfolio intends to qualify under the Internal Revenue Code with
          respect to the diversification requirements related to the
          tax-deferred status of insurance company separate accounts.

                                                     Distributions and taxes  29
<PAGE>
Shareholder's guide

          INVESTORS MAY NOT PURCHASE OR REDEEM SHARES OF THE PORTFOLIOS
          DIRECTLY. SHARES MAY BE PURCHASED OR REDEEMED ONLY THROUGH VARIABLE
          INSURANCE CONTRACTS OFFERED BY THE SEPARATE ACCOUNTS OF PARTICIPATING
          INSURANCE COMPANIES OR THROUGH QUALIFIED RETIREMENT PLANS. CERTAIN
          PORTFOLIOS MAY NOT BE AVAILABLE IN CONNECTION WITH A PARTICULAR
          CONTRACT AND CERTAIN CONTRACTS MAY LIMIT ALLOCATIONS AMONG THE
          PORTFOLIOS. REFER TO THE PROSPECTUS FOR THE PARTICIPATING INSURANCE
          COMPANY'S SEPARATE ACCOUNT OR YOUR PLAN DOCUMENTS FOR INSTRUCTIONS ON
          PURCHASING OR SELLING OF VARIABLE INSURANCE CONTRACTS AND ON HOW TO
          SELECT SPECIFIC PORTFOLIOS AS INVESTMENT OPTIONS FOR A CONTRACT OR A
          QUALIFIED PLAN.

PRICING OF PORTFOLIO SHARES

          Investments will be processed at the NAV next determined after an
          order is received and accepted by a Portfolio or its agent. In order
          to receive a day's price, your order must be received by the close of
          the regular trading session of the New York Stock Exchange any day
          that the NYSE is open. Securities of the Portfolios other than Money
          Market Portfolio are valued at market value or, if a market quotation
          is not readily available, at their fair value determined in good faith
          under procedures established by and under the supervision of the
          Trustees. Short-term instruments maturing within 60 days are valued at
          amortized cost, which approximates market value. See the SAI for more
          detailed information.

          To the extent a Portfolio holds securities that are primarily listed
          on foreign exchanges that trade on weekends or other days when the
          Portfolios do not price their shares, the NAV of a Portfolio's shares
          may change on days when shareholders will not be able to purchase or
          redeem the Portfolio's shares.

          Money Market Portfolio's securities are valued at their amortized
          cost. Amortized cost valuation involves valuing an instrument at its
          cost and thereafter assuming a constant amortization to maturity (or
          such other date as permitted by Rule 2a-7) of any discount or premium.
          If fluctuating interest rates cause the market value of the portfolio
          to deviate more than 1/2 of 1% from the value determined on the basis
          of amortized cost, the Trustees will consider whether any action, such
          as adjusting the Share's NAV to reflect current market conditions,
          should be initiated to prevent any material dilutive effect on
          shareholders.

PURCHASES

          Purchases of Shares may be made only by the separate accounts of
          insurance companies for the purpose of funding variable insurance
          contracts or by qualified plans. Refer to the prospectus of the
          appropriate insurance company separate account or your plan documents
          for information on how to invest in the Shares of each Portfolio.
          Participating insurance companies and certain other designated
          organizations are authorized to receive purchase orders on the
          Portfolios' behalf.

          The Portfolios do not permit frequent trading or market timing.
          Excessive purchases of Portfolio Shares disrupt portfolio management
          and drive Portfolio expenses higher. Each Portfolio reserves the right
          to reject any specific purchase order. Purchase orders may be refused
          if, in Janus Capital's opinion, they are of a size that would disrupt
          the management of a Portfolio. Although there is no present intention
          to do so, the Portfolios may discontinue sales of their shares if
          management and the Trustees believe that continued sales may adversely
          affect a Portfolio's ability to achieve its investment objective. If
          sales of a Portfolio's Shares are discontinued, it is expected that
          existing participants invested in that Portfolio would be permitted to
          continue to authorize investment in that Portfolio and to reinvest any
          dividends or capital gains distributions, absent highly unusual
          circumstances. The Portfolios may discontinue sales to a qualified
          plan and require plan participants with existing investments in the
          Shares to redeem those

 30 Janus Aspen Series
<PAGE>

          investments if the plan loses (or in the opinion of Janus Capital, is
          at risk of losing) its qualified plan status.

REDEMPTIONS

          Redemptions, like purchases, may be effected only through the separate
          accounts of participating insurance companies or through qualified
          plans. Please refer to the appropriate separate account prospectus or
          plan documents for details.

          Shares of any Portfolio may be redeemed on any business day.
          Redemptions are processed at the NAV next calculated after receipt and
          acceptance of the redemption order by the Portfolio or its agent.
          Redemption proceeds will normally be wired the business day following
          receipt of the redemption order, but in no event later than seven days
          after receipt of such order.

FREQUENT TRADING

          Frequent trading of Portfolio shares in response in short-term
          fluctuations in the market -- also known as "market timing" -- may
          make it very difficult to manage a Portfolio's investments. The
          Portfolios do not permit frequent trading or market timing. When
          market timing occurs, a Portfolio may have to sell portfolio
          securities to have the cash necessary to redeem the market timer's
          shares. This can happen at a time when it is not advantageous to sell
          any securities, which may harm a Portfolio's performance. When large
          dollar amounts are involved, market timing can also make it difficult
          to use long-term investment strategies because the portfolio manager
          cannot predict how much cash a Portfolio will have to invest. When in
          Janus Capital's opinion such activity would have a disruptive effect
          on portfolio management, a Portfolio reserves the right to refuse
          purchase orders and exchanges into a Portfolio by any person, group or
          commonly controlled account. A Portfolio may notify a market timer of
          rejection of a purchase or exchange order after the day the order is
          placed. If a Portfolio allows a market timer to trade Portfolio
          shares, it may require the market timer to enter into a written
          agreement to follow certain procedures and limitations.

SHAREHOLDER COMMUNICATIONS

          Shareholders will receive annual and semiannual reports including the
          financial statements of the Shares of the Portfolios that they have
          authorized for investment. Each report will show the investments owned
          by each Portfolio and the market values thereof, as well as other
          information about the Portfolios and their operations. The Trust's
          fiscal year ends December 31.

                                                         Shareholder's guide  31
<PAGE>
Financial highlights

          No Financial Highlights are presented for the Service Shares because
          the Shares did not commence operations until December 31, 1999.

 32 Janus Aspen Series
<PAGE>
                                                    Glossary of investment terms

          This glossary provides a more detailed description of some of the
          types of securities and other instruments in which the Portfolios may
          invest. The Portfolios may invest in these instruments to the extent
          permitted by their investment objectives and policies. The Portfolios
          are not limited by this discussion and may invest in any other types
          of instruments not precluded by the policies discussed elsewhere in
          this Prospectus. Please refer to the SAI for a more detailed
          discussion of certain instruments.

I. EQUITY AND DEBT SECURITIES

          BONDS are debt securities issued by a company, municipality,
          government or government agency. The issuer of a bond is required to
          pay the holder the amount of the loan (or par value of the bond) at a
          specified maturity and to make scheduled interest payments.

          COMMERCIAL PAPER is a short-term debt obligation with a maturity
          ranging from 1 to 270 days issued by banks, corporations and other
          borrowers to investors seeking to invest idle cash. The Portfolios may
          purchase commercial paper issued in private placements under Section
          4(2) of the Securities Act of 1933.

          COMMON STOCKS are equity securities representing shares of ownership
          in a company and usually carry voting rights and earns dividends.
          Unlike preferred stock, dividends on common stock are not fixed but
          are declared at the discretion of the issuer's board of directors.

          CONVERTIBLE SECURITIES are preferred stocks or bonds that pay a fixed
          dividend or interest payment and are convertible into common stock at
          a specified price or conversion ratio.

          DEBT SECURITIES are securities representing money borrowed that must
          be repaid at a later date. Such securities have specific maturities
          and usually a specific rate of interest or an original purchase
          discount.

          DEPOSITARY RECEIPTS are receipts for shares of a foreign-based
          corporation that entitle the holder to dividends and capital gains on
          the underlying security. Receipts include those issued by domestic
          banks (American Depositary Receipts), foreign banks (Global or
          European Depositary Receipts) and broker-dealers (depositary shares).

          FIXED-INCOME SECURITIES are securities that pay a specified rate of
          return. The term generally includes short-and long-term government,
          corporate and municipal obligations that pay a specified rate of
          interest or coupons for a specified period of time, and preferred
          stock, which pays fixed dividends. Coupon and dividend rates may be
          fixed for the life of the issue or, in the case of adjustable and
          floating rate securities, for a shorter period.

          HIGH-YIELD/HIGH-RISK BONDS are bonds that are rated below investment
          grade by the primary rating agencies (e.g., BB or lower by Standard &
          Poor's and Ba or lower by Moody's). Other terms commonly used to
          describe such bonds include "lower rated bonds," "noninvestment grade
          bonds" and "junk bonds."

          MORTGAGE- AND ASSET-BACKED SECURITIES are shares in a pool of
          mortgages or other debt. These securities are generally pass-through
          securities, which means that principal and interest payments on the
          underlying securities (less servicing fees) are passed through to
          shareholders on a pro rata basis. These securities involve prepayment
          risk, which is the risk that the underlying mortgages or other debt
          may be refinanced or paid off prior to their maturities during periods
          of declining interest rates. In that case, a portfolio manager may
          have to reinvest the proceeds from the securities at a lower rate.
          Potential market gains on a security subject to prepayment risk may be
          more limited than potential market gains on a comparable security that
          is not subject to prepayment risk.

          PASSIVE FOREIGN INVESTMENT COMPANIES (PFICS) are any foreign
          corporations which generate certain amounts of passive income or hold
          certain amounts of assets for the production of passive income.
          Passive income includes dividends, interest, royalties, rents and
          annuities. To avoid taxes and interest that the

                                                Glossary of investment terms  33
<PAGE>

          Portfolios must pay if these investments are profitable, the
          Portfolios may make various elections permitted by the tax laws. These
          elections could require that the Portfolios recognize taxable income,
          which in turn must be distributed, before the securities are sold and
          before cash is received to pay the distributions.

          PAY-IN-KIND BONDS are debt securities that normally give the issuer an
          option to pay cash at a coupon payment date or give the holder of the
          security a similar bond with the same coupon rate and a face value
          equal to the amount of the coupon payment that would have been made.

          PREFERRED STOCKS are equity securities that generally pay dividends at
          a specified rate and have preference over common stock in the payment
          of dividends and liquidation. Preferred stock generally does not carry
          voting rights.

          REPURCHASE AGREEMENTS involve the purchase of a security by a
          Portfolio and a simultaneous agreement by the seller (generally a bank
          or dealer) to repurchase the security from the Portfolio at a
          specified date or upon demand. This technique offers a method of
          earning income on idle cash. These securities involve the risk that
          the seller will fail to repurchase the security, as agreed. In that
          case, a Portfolio will bear the risk of market value fluctuations
          until the security can be sold and may encounter delays and incur
          costs in liquidating the security.

          REVERSE REPURCHASE AGREEMENTS involve the sale of a security by a
          Portfolio to another party (generally a bank or dealer) in return for
          cash and an agreement by the Portfolio to buy the security back at a
          specified price and time. This technique will be used primarily to
          provide cash to satisfy unusually high redemption requests, or for
          other temporary or emergency purposes.

          RULE 144A SECURITIES are securities that are not registered for sale
          to the general public under the Securities Act of 1933, but that may
          be resold to certain institutional investors.

          STANDBY COMMITMENTS are obligations purchased by a Portfolio from a
          dealer that give the Portfolio the option to sell a security to the
          dealer at a specified price.

          STEP COUPON BONDS are debt securities that trade at a discount from
          their face value and pay coupon interest. The discount from the face
          value depends on the time remaining until cash payments begin,
          prevailing interest rates, liquidity of the security and the perceived
          credit quality of the issuer.

          STRIP BONDS are debt securities that are stripped of their interest
          (usually by a financial intermediary) after the securities are issued.
          The market value of these securities generally fluctuates more in
          response to changes in interest rates than interest-paying securities
          of comparable maturity.

          TENDER OPTION BONDS are generally long-term securities that are
          coupled with an option to tender the securities to a bank,
          broker-dealer or other financial institution at periodic intervals and
          receive the face value of the bond. This type of security is commonly
          used as a means of enhancing the security's liquidity.

          U.S. GOVERNMENT SECURITIES include direct obligations of the U.S.
          government that are supported by its full faith and credit. Treasury
          bills have initial maturities of less than one year, Treasury notes
          have initial maturities of one to ten years and Treasury bonds may be
          issued with any maturity but generally have maturities of at least ten
          years. U.S. government securities also include indirect obligations of
          the U.S. government that are issued by federal agencies and government
          sponsored entities. Unlike Treasury securities, agency securities
          generally are not backed by the full faith and credit of the U.S.
          government. Some agency securities are supported by the right of the
          issuer to borrow from the Treasury, others are supported by the
          discretionary authority of the U.S. government to purchase the
          agency's obligations and others are supported only by the credit of
          the sponsoring agency.

 34 Janus Aspen Series
<PAGE>

          VARIABLE AND FLOATING RATE SECURITIES have variable or floating rates
          of interest and, under certain limited circumstances, may have varying
          principal amounts. These securities pay interest at rates that are
          adjusted periodically according to a specified formula, usually with
          reference to some interest rate index or market interest rate. The
          floating rate tends to decrease the security's price sensitivity to
          changes in interest rates.

          WARRANTS are securities, typically issued with preferred stock or
          bonds, that give the holder the right to buy a proportionate amount of
          common stock at a specified price, usually at a price that is higher
          than the market price at the time of issuance of the warrant. The
          right may last for a period of years or indefinitely.

          WHEN-ISSUED, DELAYED DELIVERY AND FORWARD TRANSACTIONS generally
          involve the purchase of a security with payment and delivery at some
          time in the future - i.e., beyond normal settlement. The Portfolios do
          not earn interest on such securities until settlement and bear the
          risk of market value fluctuations in between the purchase and
          settlement dates. New issues of stocks and bonds, private placements
          and U.S. government securities may be sold in this manner.

          ZERO COUPON BONDS are debt securities that do not pay regular interest
          at regular intervals, but are issued at a discount from face value.
          The discount approximates the total amount of interest the security
          will accrue from the date of issuance to maturity. The market value of
          these securities generally fluctuates more in response to changes in
          interest rates than interest-paying securities.

II. FUTURES, OPTIONS AND OTHER DERIVATIVES

          FORWARD CONTRACTS are contracts to purchase or sell a specified amount
          of a financial instrument for an agreed upon price at a specified
          time. Forward contracts are not currently exchange traded and are
          typically negotiated on an individual basis. The Portfolios may enter
          into forward currency contracts to hedge against declines in the value
          of securities denominated in, or whose value is tied to, a currency
          other than the U.S. dollar or to reduce the impact of currency
          appreciation on purchases of such securities. They may also enter into
          forward contracts to purchase or sell securities or other financial
          indices.

          FUTURES CONTRACTS are contracts that obligate the buyer to receive and
          the seller to deliver an instrument or money at a specified price on a
          specified date. The Portfolios may buy and sell futures contracts on
          foreign currencies, securities and financial indices including
          interest rates or an index of U.S. government, foreign government,
          equity or fixed-income securities. The Portfolios may also buy options
          on futures contracts. An option on a futures contract gives the buyer
          the right, but not the obligation, to buy or sell a futures contract
          at a specified price on or before a specified date. Futures contracts
          and options on futures are standardized and traded on designated
          exchanges.

          INDEXED/STRUCTURED SECURITIES are typically short- to
          intermediate-term debt securities whose value at maturity or interest
          rate is linked to currencies, interest rates, equity securities,
          indices, commodity prices or other financial indicators. Such
          securities may be positively or negatively indexed (i.e. their value
          may increase or decrease if the reference index or instrument
          appreciates). Indexed/structured securities may have return
          characteristics similar to direct investments in the underlying
          instruments and may be more volatile than the underlying instruments.
          A Portfolio bears the market risk of an investment in the underlying
          instruments, as well as the credit risk of the issuer.

          INTEREST RATE SWAPS involve the exchange by two parties of their
          respective commitments to pay or receive interest (e.g., an exchange
          of floating rate payments for fixed rate payments).

          INVERSE FLOATERS are debt instruments whose interest rate bears an
          inverse relationship to the interest rate on another instrument or
          index. For example, upon reset the interest rate payable on a security
          may go down when the underlying index has risen. Certain inverse
          floaters may have an interest rate reset

                                                Glossary of investment terms  35
<PAGE>

          mechanism that multiplies the effects of change in the underlying
          index. Such mechanism may increase the volatility of the security's
          market value.

          OPTIONS are the right, but not the obligation, to buy or sell a
          specified amount of securities or other assets on or before a fixed
          date at a predetermined price. The Portfolios may purchase and write
          put and call options on securities, securities indices and foreign
          currencies.

 36 Janus Aspen Series
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[JANUS LOGO]

        1-800-525-0020
        100 Fillmore Street
        Denver, Colorado 80206-4928
        janus.com

You can request other information, including a Statement of
Additional Information, free of charge, by contacting your plan
sponsor or visiting our Web site at janus.com. Other information is
also available from financial intermediaries that sell Shares of the
Portfolios.

The Statement of Additional Information provides detailed
information about the Portfolios and is incorporated into this
Prospectus by reference. You may review the Portfolios' Statement of
Additional Information at the Public Reference Room of the SEC or
get text only copies for a fee, by writing to or calling the Public
Reference Room, Washington, D.C. 20549-6009 (1-800-SEC-0330). You
may obtain the Statement of Additional Information for free from the
SEC's Web site at http://www.sec.gov.

                    Investment Company Act File No. 811-7736



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