JANUS INVESTMENT FUND, 497, 2000-02-02

JANUS INVESTMENT FUND
497, 2000-02-02

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[JANUS LOGO]
JANUS FUND
PROSPECTUS

JANUARY 31, 2000

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>

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TABLE OF CONTENTS
- --------------------------------------------------------------------------------

<TABLE>
<S> <C>
RISK/RETURN SUMMARY
Janus Fund................................... 2
Fees and expenses............................ 4
INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT
STRATEGIES AND RISKS
Investment objective and principal investment
strategies................................... 5
General portfolio policies................... 6
Risks........................................ 9
SHAREHOLDER'S MANUAL
Minimum investments.......................... 15
Types of account ownership................... 15
To purchase shares........................... 18
To exchange shares........................... 19
To redeem shares............................. 19
Shareholder services and account policies.... 23
MANAGEMENT OF THE FUND
Investment adviser........................... 27
Portfolio manager............................ 28
Assistant portfolio managers................. 28
OTHER INFORMATION............... ............... 30
DISTRIBUTIONS AND TAXES
Distributions................................ 32
Taxes........................................ 33
FINANCIAL HIGHLIGHTS.............. ............. 35
GLOSSARY
Glossary of investment terms................. 37
</TABLE>

Janus Fund prospectus 1
<PAGE>

RISK/RETURN SUMMARY
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JANUS FUND

1. WHAT IS THE INVESTMENT OBJECTIVE OF JANUS FUND?

The Fund seeks long-term growth of capital in a manner consistent
with the preservation of capital.

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

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF JANUS FUND?

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

The Fund may invest without limit in foreign equity and debt
securities and less than 35% of its net assets in
high-yield/high-risk bonds.

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 such investments, a significant portion of the
Fund's assets may be in cash or similar investments.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN JANUS FUND?

The biggest risk of investing in this Fund is that its returns
may vary and you could lose money. If you are considering
investing in the Fund, 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 Fund's portfolio may decrease if the value of an
individual company in the portfolio decreases. The value of the
Fund's portfolio could also decrease if the stock market goes

2 Janus Fund prospectus
<PAGE>

down. If the value of the Fund's portfolio decreases, the Fund's
net asset value (NAV) will also decrease which means if you sell
your shares in the Fund you would get back less money.

An investment in the Fund 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 illustrates how the Fund's performance
has varied over time. The bar chart depicts the change in the
Fund's performance from year-to-year during the periods
indicated. The table compares the Fund's average annual returns
for the periods indicated to a broad-based securities market
index.

JANUS FUND

A BAR CHART showing Annual Total Returns for Janus Fund from
1990 through 1999:

Annual returns for periods ended 12/31
<TABLE>
<S> <C> <C> <C> <C> <C> <C> <C> <C> <C>
(0.74%) 42.80% 6.87% 10.92% (1.10%) 29.43% 19.61% 22.72% 38.89% 47.13%
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Each percentage is represented by a bar of proportionate size
with the actual total return printed above the bar.

Best Quarter: 4th-1998 28.44% Worst Quarter: 3rd-1990 (13.91%)
</TABLE>

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

<TABLE>
<CAPTION>
Since Inception
1 year 5 years 10 years (2/5/70)
<S> <C> <C> <C> <C>
Janus Fund 47.13% 31.10% 20.49% 18.49%
S&P 500 Index* 21.03% 28.59% 18.19% 14.03%
-------------------------------------------------
</TABLE>

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

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

Janus Fund prospectus 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 Fund.

ANNUAL FUND OPERATING EXPENSES are paid out of the Fund'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 describes the fees and expenses that you may pay if
you buy and hold shares of the Fund. It is based upon gross
expenses (without the effect of expense offset arrangements). All
of the fees and expenses shown were determined based on net
assets as of the fiscal year ended October 31, 1999.

<TABLE>
<CAPTION>
Janus Fund
<S> <C>
Management Fee(1) 0.65%
Other Expenses 0.20%
Total Annual Fund Operating Expenses 0.85%
</TABLE>

- --------------------------------------------------------------------------------
(1) "Management Fee" information has been restated to reflect a new fee
schedule effective January 31, 2000.
- --------------------------------------------------------------------------------

EXAMPLE:
This example is intended to help you compare the cost of investing in the
Fund with the cost of investing in other mutual funds. The example
assumes that you invest $10,000 in the Fund 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 Fund'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 5 Years 10 Years
----------------------------------------
<S> <C> <C> <C> <C>
Janus Fund $87 $271 $471 $1,049
</TABLE>

4 Janus Fund prospectus
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INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT
STRATEGIES AND RISKS
- --------------------------------------------------------------------------------

This section takes a closer look at the investment objective of
the Fund, its principal investment strategies and certain risks
of investing in the Fund. 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 9-11 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

Janus Fund 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 Fund can invest in companies
of any size, it generally invests in larger, more established
companies.

The Fund may invest substantially all of its assets in common
stocks if its 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 Fund. Income realized on the Fund's
investments will be incidental to its objective.

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.

Janus Fund prospectus 5
<PAGE>

There are no limitations on the countries in which the Fund may
invest and the Fund may at times have significant foreign
exposure.

GENERAL PORTFOLIO POLICIES

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

CASH POSITION
When the Fund's portfolio manager believes that market conditions
are unfavorable for profitable investing, or when he is otherwise
unable to locate attractive investment opportunities, the Fund's
cash or similar investments may increase. In other words, the
Fund does not always stay fully invested in stocks. 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 Fund's
cash position to protect its assets or maintain liquidity. When
the Fund'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 Fund remained more fully invested in
stocks.

OTHER TYPES OF INVESTMENTS
The Fund invests primarily in domestic and foreign equity
securities, which may include preferred stocks, common stocks,
warrants and securities convertible into common or preferred
stocks, but it 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

6 Janus Fund prospectus
<PAGE>

- high-yield/high-risk bonds (less than 35% of the Fund'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 Fund 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 the 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 Fund's Trustees,
certain restricted securities may be deemed liquid, and will not
be counted toward this 15% limit.

FOREIGN SECURITIES
The Fund may invest without limit in foreign equity and debt
securities. The Fund 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
The Fund may invest in special situations. A special situation
arises when, in the opinion of the Fund's portfolio 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 Fund's performance could suffer if the
anticipated development in

Janus Fund prospectus 7
<PAGE>

a "special situation" investment does not occur or does not
attract the expected attention.

PORTFOLIO TURNOVER
The Fund generally intends to purchase securities for long-term
investment although, to a limited extent, the Fund 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 Fund 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 Fund's portfolio
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
the Fund's performance.

8 Janus Fund prospectus
<PAGE>

RISKS

Because the Fund 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 Fund's share price may
also decrease. The Fund'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 fund with a small asset base. A fund 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 Fund.

1. HOW COULD THE FUND'S INVESTMENTS IN FOREIGN SECURITIES AFFECT ITS
PERFORMANCE?

The Fund 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 Fund's performance may depend on
issues other than the performance of a particular company. These
issues include:

- currency risk

- political and economic risk

- regulatory risk

- market risk

- transaction costs

These risks are described in the SAI.

Janus Fund prospectus 9
<PAGE>

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 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 FUND TRY TO REDUCE RISK?

The Fund 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 Fund 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 Fund. However, the Fund's performance could be worse
than if the Fund 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.

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

10 Janus Fund prospectus
<PAGE>

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.

5. I'VE HEARD A LOT ABOUT HOW THE CHANGE TO THE YEAR 2000 COULD AFFECT COMPUTER
SYSTEMS. DOES THIS CREATE ANY SPECIAL RISKS?

The portfolio manager carefully researches each potential
investment before making an investment decision and, among other
things considers what impact, if any, the Year 2000 transition
has had on the company's operations when selecting portfolio
holdings. However, there is no guarantee that the information the
portfolio manager receives regarding a company's Year 2000
transition status is completely accurate. If a company has not
satisfactorily addressed Year 2000 issues, the Fund's performance
could suffer.

Janus Fund prospectus 11
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<PAGE>

[JANUS LOGO]
Janus Fund
SHAREHOLDER'S MANUAL

This section will help you
become familiar with the
different types of accounts
you can establish with Janus.
It also explains in detail the
wide array of services and
features you can establish on
your account, as well as
account policies and fees that
may apply to your account.
Account policies (including
fees), services and features
may be modified or
discontinued without
shareholder approval or prior
notice.

[JANUS LOGO]

<PAGE>

HOW TO GET IN TOUCH WITH JANUS

INVESTOR SERVICE CENTERS
100 Fillmore Street, Suite 100
Denver, CO 80206

3773 Cherry Creek North Drive, Suite 101
Denver, CO 80209

(Hours: Monday-Friday 7:00 a.m.-6:00 p.m., and Saturday 9:00 a.m.-1:00 p.m.,
Mountain time.)

MAILING ADDRESS
Janus
P.O. Box 173375
Denver, CO 80217-3375

FOR OVERNIGHT CARRIER
Janus
Suite 101
3773 Cherry Creek Drive North
Denver, CO 80209-3821

INVESTOR SERVICE REPRESENTATIVES
If you have any questions while reading this Prospectus, please call one of our
Investor Service Representatives at 1-800-525-3713 Monday-Friday: 8:00 a.m.-8:00
p.m., and Saturday: 10:00 a.m.-4:00 p.m., New York time.

JANUS XPRESSLINE(TM)
1-888-979-7737

JANUS INTERNET ADDRESS
JANUS.COM

For 24-hour access to account and fund information, exchanges, purchases and
redemptions, automated daily quotes on fund share prices, yields and total
returns.

JANUS.COM SPECIALISTS
1-800-975-9932

TDD
1-800-525-0056
A telecommunications device for our hearing- and speech-impaired shareholders.

JANUS LITERATURE LINE
1-800-525-8983
To request a prospectus, shareholder reports or marketing materials 24 hours a
day.

14 Shareholder's manual
<PAGE>

MINIMUM INVESTMENTS*

<TABLE>
<S> <C>
To open a new regular
account $2,500
To open a new
retirement account,
education account or
UGMA/UTMA $ 500
To open a new regular
account with an
Automatic Investment
Program $ 500**
To add to any type of
an account $ 100+
</TABLE>

* The Fund reserves the right to change the amount of these minimums from time
to time or to waive them in whole or in part for certain types of accounts.

** An Automatic Investment Program requires a $100 minimum automatic investment
per month until the account balance reaches $2,500.

+ The minimum subsequent investment for a retirement account or UGMA/UTMA is
$50.

TYPES OF ACCOUNT OWNERSHIP

If you are investing in the Fund for the first time, you will
need to establish an account. You can establish the following
types of accounts by completing a New Account Application.

INDIVIDUAL OR JOINT OWNERSHIP
Individual accounts are owned by one person. Joint accounts have
two or more owners.

A GIFT OR TRANSFER TO MINOR (UGMA OR UTMA)
An UGMA/UTMA is a custodial account managed for the benefit of a
minor. To open an UGMA or UTMA, you must include the minor's
Social Security number on the application.

TRUST
An established trust can open an account. The names of each
trustee, the name of the trust and the date of the trust
agreement must be included on the application.

Shareholder's manual 15
<PAGE>

BUSINESS ACCOUNTS
Corporations and partnerships may also open an account. The
application must be signed by an authorized officer of the
corporation or a general partner of the partnership.

TAX-DEFERRED ACCOUNTS

If you are eligible, you may set up one or more tax-deferred
accounts. A tax-deferred account allows you to shelter your
investment income and capital gains from current income taxes. A
contribution to certain of these plans may also be tax
deductible. Tax-deferred accounts include retirement plans
described below and the Education IRA. Please refer to the Janus
retirement guide for more complete information regarding the
different types of IRAs, including the Education IRA.
Distributions from these plans are generally subject to income
tax and may be subject to an additional tax if withdrawn prior to
age 59 1/2 or used for a nonqualifying purpose. Investors should
consult their tax adviser or legal counsel before selecting a
tax-deferred account.

Investors Fiduciary Trust Company serves as custodian for the
tax-deferred accounts offered by the Fund. You will be charged an
annual account maintenance fee of $12 for each taxpayer
identification number no matter how many tax-deferred accounts
you have with Janus. You may pay the fee by check or have it
automatically deducted from your account (usually in December).
The custodian reserves the right to change the amount of this fee
or to waive it in whole or in part for certain types of accounts.

TRADITIONAL AND ROTH INDIVIDUAL RETIREMENT ACCOUNTS
Both types of IRAs allow most individuals with earned income to
contribute up to the lesser of $2,000 ($4,000 for most married
couples) or 100% of compensation annually.

EDUCATION IRA
This plan allows individuals, subject to certain income
limitations, to contribute up to $500 annually on behalf of any
child under the age of 18.

16 Shareholder's manual
<PAGE>

SIMPLIFIED EMPLOYEE PENSION PLAN
This plan allows small business owners (including sole
proprietors) to make tax-deductible contributions for themselves
and any eligible employee(s). A SEP requires an IRA (a SEP-IRA)
to be set up for each SEP participant.

PROFIT SHARING OR MONEY PURCHASE PENSION PLAN
These plans are open to corporations, partnerships and sole
proprietors to benefit their employees and themselves.

SECTION 403(B)(7) PLAN
Employees of educational organizations or other qualifying, tax-
exempt organizations may be eligible to participate in a Section
403(b)(7) Plan.

PLEASE REFER TO THE CHART ON THE FOLLOWING PAGES FOR INFORMATION
ON OPENING AN ACCOUNT AND CONDUCTING BUSINESS WITH JANUS. WITH
CERTAIN LIMITED EXCEPTIONS, THE FUND IS AVAILABLE ONLY TO U.S.
CITIZENS OR RESIDENTS. WHEN YOU PURCHASE, EXCHANGE, OR REDEEM
SHARES, YOUR REQUEST WILL BE PROCESSED AT THE NEXT NAV CALCULATED
AFTER YOUR ORDER IS RECEIVED AND ACCEPTED.

Shareholder's manual 17
<PAGE>

TO PURCHASE SHARES

BY MAIL/IN WRITING
------------------------------------------------------------------------------

- To open your account, complete and sign the appropriate application and make
your check payable to Janus.

- To purchase additional shares, complete the remittance slip attached at the
bottom of your confirmation statement. If you are making a purchase into a
retirement account, please indicate whether the purchase is a rollover or a
current or prior year contribution. Send your check and remittance slip or
written instructions to the address listed on the slip.

BY TELEPHONE
------------------------------------------------------------------------------

- The "Telephone Purchase of Shares Option" allows you to purchase additional
shares quickly and conveniently through an electronic transfer of money.
After establishing this option on your account, call an Investor Service
Representative during normal business hours or the Janus XpressLine for
access to this option 24 hours a day. Janus will automatically debit your
predesignated bank account.

- Purchases may also be made by wiring money from your bank account to your
Janus account. Call an Investor Service Representative for wiring
instructions.

BY INTERNET
------------------------------------------------------------------------------

- The "Telephone Purchase of Shares Option" allows you to make a purchase into
an existing account on our Web site at janus.com.

BY AUTOMATIC INVESTMENT
------------------------------------------------------------------------------

- Automatic Monthly Investment Program - You select the day each month that
your money ($100 minimum) will be electronically transferred from your bank
account to your Fund account.

- Payroll Deduction - If your employer can initiate an automatic payroll
deduction, you may have all or a portion of your paycheck ($100 minimum)
invested directly into your Fund account.

18 Shareholder's manual
<PAGE>

<TABLE>
<S> <C>
TO EXCHANGE SHARES TO REDEEM SHARES
- --------------------------------------- ---------------------------------------
- To request an exchange in writing, - To request a redemption in writ-
please follow the instructions for ing, please follow the instructions
written requests on page 22. Also for written requests on page 22.
refer to the exchange policies - Please see page 21 for information
listed on page 20 for more infor- about payment of redemption
mation. proceeds.

- --------------------------------------- ---------------------------------------
- All accounts are automatically eli- - The telephone redemption option
gible to exchange shares by tele- enables you to request redemp-
phone. To exchange all or a portion tions daily from your account by
of your shares into any other calling an Investor Service Repre-
available Janus fund, call an sentative by the close of the
Investor Service Representative or regular trading session of the
the Janus XpressLine. NYSE, normally 4:00 p.m. New York
time. You may also use Janus
XpressLine for access to this
option 24 hours a day.

- --------------------------------------- ---------------------------------------
- Exchanges may be made on our Web - Redemptions may be made on our Web
site at janus.com. site at janus.com.
- --------------------------------------- ---------------------------------------
- Systematic Exchange - You deter- - Systematic Redemption - This option
mine the amount of money you would allows you to redeem a specific
like automatically exchanged from dollar amount from your account on
one Janus account to another on any a regular basis.
day of the month. You may establish
this program for as little as $100
per month on existing accounts. You
may establish a new account with a
$500 initial purchase and subse-
quent $100 systematic exchanges.
</TABLE>

Shareholder's manual 19
<PAGE>

PAYING FOR SHARES

Please note the following when purchasing shares:

- - Cash, credit cards, third party checks, travelers cheques, credit card checks
or money orders will not be accepted.

- - All purchases must be made in U.S. dollars and checks must be drawn on U.S.
banks.

- - We may make additional attempts to debit the bank account for ACH purchases.

- - The Fund reserves the right to reject any specific purchase request.

- - If all or a portion of a check is received for investment without a specific
fund designation, the undesignated amount will be invested in the Janus Money
Market Fund -- Investor Shares. Shares that are subsequently exchanged from
Janus Money Market Fund -- Investor Shares into the selected Fund will receive
the NAV next calculated after your order is received and accepted by the Fund.

- - If your purchase is cancelled, you will be responsible for any losses or fees
imposed by your bank and losses that may be incurred as a result of any
decline in the value of the cancelled purchase.

EXCHANGE POLICIES

The exchange privilege is not intended as a vehicle for short-term or excessive
trading. The Funds do not permit excessive trading or market timing. Excessive
purchases, redemptions, or exchanges of Fund shares disrupt portfolio management
and drive Fund expenses higher.

Please note the following when exchanging shares:

- - Except for Systematic Exchanges, new accounts established by exchange must be
opened with $2,500 or the total account value if the value of the account you
are exchanging from is less than $2,500.

- - Exchanges between existing accounts must meet the $100 subsequent investment
requirement.

- - You may make four exchanges out of the Fund during a calendar year (exclusive
of Systematic Exchange). Exchanges in excess of this limit are considered
excessive trading and may be subject to an exchange fee or may result in
termination of the exchange privilege or the right to make future purchases of
Fund shares.

20 Shareholder's manual
<PAGE>

- - The Fund reserves the right to reject any purchase order or exchange request
and to modify or terminate the exchange privilege at any time. For example,
the Fund may reject exchanges from accounts engaged in or known to engage in
trading in excess of the limit above (including market timing transactions) or
whose trading has been or may be disruptive to a Fund.

- - Exchanges between accounts will be accepted only if the registrations are
identical.

- - If the shares you are exchanging are held in certificate form, you must return
the certificate to Janus prior to making any exchanges. Effective June 4,
1999, shares are no longer available in certificate form.

- - An exchange represents the sale of shares from one Fund and the purchase of
shares of another Fund, which may produce a taxable gain or loss in a
non-retirement account.

- - If the balance in the account you are exchanging from falls below the
systematic exchange amount, all remaining shares will be exchanged
and the program will be discontinued.

PAYMENT OF REDEMPTION PROCEEDS

- - BY CHECK - Redemption proceeds will be sent to the shareholder(s) of record at
the address of record within seven days after receipt of a valid redemption
request. During the 10 days following an address change, checks sent to a new
address require a signature guarantee.

- - BY ELECTRONIC TRANSFER - If you have established the electronic redemption
option, your redemption proceeds can be electronically transferred to your
predesignated bank account on the next bank business day after receipt of your
redemption request (wire transfer) or the second bank business day after
receipt of your redemption request (ACH transfer).

Wire transfers will be charged an $8 fee per wire and your bank may charge an
additional fee to receive the wire. Wire redemptions are not available for
retirement accounts.

IF THE SHARES BEING REDEEMED WERE PURCHASED BY CHECK, TELEPHONE, ON OUR WEB
SITE, OR THROUGH THE AUTOMATIC MONTHLY INVESTMENT PROGRAM, THE FUND MAY DELAY
THE PAYMENT OF YOUR REDEMPTION PROCEEDS FOR UP TO 15 DAYS FROM THE DAY OF
PURCHASE TO ALLOW THE PURCHASE TO CLEAR. Unless you provide alternate
instructions, your proceeds will be invested in Janus Money Market
Fund - Investor Shares during the 15 day hold period.

Shareholder's manual 21
<PAGE>

WRITTEN INSTRUCTIONS

To redeem or exchange all or part of your shares in writing, your
request should be sent to one of the addresses listed on page 14
and must include the following information:

- the name of the Fund(s)

- the account number(s)

- the amount of money or number of shares being redeemed or
exchanged

- the name(s) on the account

- the signature(s) of all registered account owners (see account
application for signature requirements)

- your daytime telephone number

SIGNATURE GUARANTEE

A SIGNATURE GUARANTEE IS REQUIRED if any of the following is
applicable:

- You request a redemption by check that exceeds $100,000.

- You would like a check made payable to anyone other than the
shareholder(s) of record.

- You would like a check mailed to an address which has been
changed within 10 days of the redemption request.

- You would like a check mailed to an address other than the
address of record.

THE FUND RESERVES THE RIGHT TO REQUIRE A SIGNATURE GUARANTEE
UNDER OTHER CIRCUMSTANCES OR TO REJECT OR DELAY A REDEMPTION ON
CERTAIN LEGAL GROUNDS.

HOW TO OBTAIN A SIGNATURE GUARANTEE

A signature guarantee assures that a signature is genuine. The
signature guarantee protects shareholders from unauthorized
account transfers. The following financial institutions may
guaran-

22 Shareholder's manual
<PAGE>

tee signatures: banks, savings and loan associations, trust
companies, credit unions, broker-dealers, and member firms of a
national securities exchange. Call your financial institution to
see if they have the ability to guarantee a signature. A
signature guarantee cannot be provided by a notary public.

If you live outside the United States, a foreign bank properly
authorized to do business in your country of residence or a U.S.
consulate may be able to authenticate your signature.

PRICING OF FUND SHARES

All purchases, redemptions and exchanges will be processed at the
NAV next calculated after your request is received and accepted
by the Fund (or the Fund's agent or authorized designee). The
Fund's NAV is calculated at the close of the regular trading
session of the NYSE (normally 4:00 p.m. New York time) each day
that the NYSE is open. The NAV of Fund shares is not determined
on days the NYSE is closed (generally New Year's Day, Martin
Luther King Day, Presidents' Day, Good Friday, Memorial Day,
Independence Day, Labor Day, Thanksgiving and Christmas). In
order to receive a day's price, your order must be received by
the close of the regular trading session of the NYSE. Securities
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.

SHAREHOLDER SERVICES AND ACCOUNT POLICIES

ACCOUNT MINIMUMS

Due to the proportionately higher costs of maintaining small
accounts, Janus reserves the right to deduct a $10 minimum
balance fee (or the value of the account if less than $10) from
accounts with values below the minimums described on page 15 or
to close such accounts. This policy will apply to accounts

Shareholder's manual 23
<PAGE>

participating in the Automatic Monthly Investment Program only if
your account balance does not reach the required minimum initial
investment or falls below such minimum and you have discontinued
monthly investments. This policy does not apply to accounts that
fall below the minimums solely as a result of market value
fluctuations. It is expected that, for purposes of this policy,
accounts will be valued in September, and the $10 fee will be
assessed on the second Friday of September of each year. You will
receive notice before we charge the $10 fee or close your account
so that you may increase your account balance to the required
minimum.

TRANSACTIONS THROUGH PROCESSING ORGANIZATIONS

You may purchase or sell Fund shares through a broker-dealer,
bank or other financial institution, or an organization that
provides recordkeeping and consulting services to 401(k) plans or
other employee benefit plans (a "Processing Organization").
Processing Organizations may charge you a fee for this service
and may require different minimum initial and subsequent
investments than the Fund. Processing Organizations may also
impose other charges or restrictions different from those
applicable to shareholders who invest in the Fund directly. A
Processing Organization, rather than its customers, may be the
shareholder of record of your shares. The Fund is not responsible
for the failure of any Processing Organization to carry out its
obligations to its customers. Certain Processing Organizations
may receive compensation from Janus Capital or its affiliates and
certain Processing Organizations may receive compensation from
the Fund for shareholder recordkeeping and similar services.

TAXPAYER IDENTIFICATION NUMBER

On the application or other appropriate form, you will be asked
to certify that your Social Security or taxpayer identification
number is correct and that you are not subject to backup
withholding for failing to report income to the IRS. If you are
subject to the 31% backup withholding or you did not certify

24 Shareholder's manual
<PAGE>

your taxpayer identification number, the IRS requires the Fund to
withhold 31% of any dividends paid and redemption or exchange
proceeds. In addition to the 31% backup withholding, you may be
subject to a $50 fee to reimburse the Fund for any penalty that
the IRS may impose.

INVOLUNTARY REDEMPTIONS

The Fund reserves the right to close an account if the
shareholder is deemed to engage in activities which are illegal
or otherwise believed to be detrimental to the Fund.

TELEPHONE TRANSACTIONS

You may initiate many transactions by telephone. The Fund and its
agents will not be responsible for any losses resulting from
unauthorized transactions when procedures designed to verify the
identity of the caller are followed.

It may be difficult to reach an Investor Service Representative
by telephone during periods of unusual market activity. If you
are unable to reach a representative by telephone, please
consider sending written instructions, stopping by a Service
Center, calling the Janus XpressLine or visiting our Web site.

TEMPORARY SUSPENSION OF SERVICES

The Fund or its agents may, in case of emergency, temporarily
suspend telephone transactions and other shareholder services.

ADDRESS CHANGES

To change the address on your account, call 1-800-525-3713 or
send a written request signed by the shareholder(s) of record.
Include the name of your Fund, the account number(s), the name(s)
on the account and both the old and new addresses. Certain
options may be suspended for 10 days following an address change
unless a signature guarantee is provided.

Shareholder's manual 25
<PAGE>

REGISTRATION CHANGES

To change the name on an account, the shares are generally
transferred to a new account. In some cases, legal documentation
may be required. For further instructions, please call an
Investor Service Representative.

STATEMENTS AND REPORTS

Investors will receive quarterly confirmations of all
transactions. Quarterly statements for all investors are
available on our Web site. You may make an election on our Web
site to discontinue delivery of your paper statements. Dividend
information will be distributed annually. In addition, the Fund
will send you an immediate transaction confirmation statement
after every non-systematic transaction.

The Fund produces financial reports, which include a list of the
Fund's portfolio holdings, semiannually and updates its
prospectus annually. To reduce expenses, the Fund may choose to
mail only one report or prospectus to your household, even if
more than one person in the household has a Fund account. Please
call 1-800-525-3713 if you would like to receive additional
reports or prospectuses. The Fund reserves the right to charge a
fee for additional statement requests.

26 Shareholder's manual
<PAGE>

MANAGEMENT OF THE FUND
- --------------------------------------------------------------------------------

INVESTMENT ADVISER

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

Janus Capital began serving as investment adviser to the Fund in
1970 and currently serves as investment adviser to all of the
Janus 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 Fund's investments. Janus Capital also furnishes
certain administrative, compliance and accounting services for
the Fund, and may be reimbursed by the Fund 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 Fund and pays the salaries, fees and expenses of
all Fund officers and those Trustees who are affiliated with
Janus Capital.

The Fund pays Janus Capital a management fee which is calculated
daily and paid monthly. The advisory agreement with the Fund
spells out the management fee and other expenses that the Fund
must pay.

The Fund incurs expenses not assumed by Janus Capital, including
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. For the most recent fiscal year the
Fund paid Janus Capital a management fee equal to 0.65% of
average daily net assets.

Janus Fund prospectus 27
<PAGE>

PORTFOLIO MANAGER

BLAINE P. ROLLINS
- --------------------------------------------------------------------------------
is Executive Vice President and portfolio manager of the
Fund. Mr. Rollins served as Executive Vice President and
portfolio manager of Janus Balanced Fund, from January
1996 through December 1999 Executive Vice President, and
portfolio manager of Janus Equity Income Fund from June
1996 through December 1999, and an assistant portfolio
manager of Janus Fund from January 1994 through December
1999. Mr. Rollins joined Janus Capital in 1990 and gained
experience as a fixed-income trader and equity research
analyst prior to managing Janus Balanced Fund. He holds a
Bachelor of Science in Finance from the University of
Colorado is a Chartered Financial Analyst.

ASSISTANT PORTFOLIO MANAGERS

DAVID C. DECKER
- --------------------------------------------------------------------------------
is an assistant portfolio manager of the Fund. He is
Executive Vice President and portfolio manager of Janus
Special Situations Fund and Janus Strategic Value Fund,
both of which he has managed since inception. He joined
Janus Capital in 1992 as a research analyst and focused on
companies in the automotive and defense industries prior
to managing Janus Special Situations Fund. He obtained his
Master 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 is a Chartered Financial Analyst.

28 Janus Fund prospectus
<PAGE>

KAREN L. REIDY
- --------------------------------------------------------------------------------
is an assistant portfolio manager of the Fund. She is also
Executive Vice President and portfolio manager of Janus
Balanced Fund and Janus Equity Income 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 is a
Chartered Financial Analyst.

JOHN H. SCHREIBER
- --------------------------------------------------------------------------------
is an assistant portfolio manager of the Fund. Mr.
Schreiber joined Janus Capital in 1997 as an equity
research analyst. Prior to joining Janus Capital, 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 a Master
of Business Administration from Harvard University. He is
a Chartered Financial Analyst.

Janus Fund prospectus 29
<PAGE>

OTHER INFORMATION
- --------------------------------------------------------------------------------

SIZE OF THE FUND

Although there is no present intention to do so, the Fund may
discontinue sales of its shares if management and the Trustees
believe that continued sales may adversely affect the Fund's
ability to achieve its investment objective. If sales of the Fund
are discontinued, it is expected that existing shareholders of
the Fund would be permitted to continue to purchase shares and to
reinvest any dividends or capital gains distributions, absent
highly unusual circumstances.

YEAR 2000

Preparing for Year 2000 has been a high priority for Janus
Capital. A dedicated group was established to address this issue.
Janus Capital devoted considerable internal resources and engaged
one of the foremost experts in the field to achieve Year 2000
readiness. Janus Capital successfully completed all five steps of
its Year 2000 preparedness plans including the upgrade and
replacement of all systems, as well as full-scale testing and
implementation of those systems. Janus Capital's detailed
contingency plans were also thoroughly tested. As of the date of
this prospectus, Janus Capital has not seen any adverse impact as
a result of the Year 2000 transition on any of its systems or
those of its vendors, or on the companies in which the Funds
invest or worldwide markets and economies. Nonetheless, Janus
Capital will continue to monitor the effect of the Year 2000
transition, and there can be no absolute assurance that Year 2000
issues will not in the future adversely affect the Funds' or
Janus Capital's operations.

30 Janus Fund prospectus
<PAGE>

DISTRIBUTION OF THE FUND

The Fund 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.

Janus Fund prospectus 31
<PAGE>

DISTRIBUTIONS AND TAXES
- --------------------------------------------------------------------------------

DISTRIBUTIONS

To avoid taxation of the Fund, the Internal Revenue Code requires
the Fund to distribute net income and any net capital gains
realized on its investments annually. The Fund'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. Dividends and capital gains distributions are
normally declared and paid in December.

HOW DISTRIBUTIONS AFFECT THE FUND'S NAV

Distributions are paid to shareholders as of the record date of
the distribution of the Fund, regardless of how long the shares
have been held. Dividends and capital gains awaiting distribution
are included in the Fund's daily NAV. The share price of the Fund
drops by the amount of the distribution, net of any subsequent
market fluctuations. As an example, assume that on December 31,
the Fund declared a dividend in the amount of $0.25 per share. If
the Fund's share price was $10.00 on December 30, the Fund's
share price on December 31 would be $9.75, barring market
fluctuations. Shareholders should be aware that distributions
from a taxable mutual fund are not value-enhancing and may create
income tax obligations.

"BUYING A DIVIDEND"

If you purchase shares of the Fund just before the distribution,
you will pay the full price for the shares and receive a portion
of the purchase price back as a taxable distribution. This is
referred to as "buying a dividend." In the above example, if you
bought shares on December 30, you would have paid $10.00 per
share. On December 31, the Fund would pay you $0.25 per share as
a dividend and your shares would now be worth $9.75 per share.
Unless your account is set up as a tax-deferred account,
dividends paid to you would be included in your gross income for
tax purposes, even though you may not have participated in the

32 Janus Fund prospectus
<PAGE>

increase in NAV of the Fund, whether or not you reinvested the
dividends.

DISTRIBUTION OPTIONS

When you open an account, you must specify on your application
how you want to receive your distributions. You may change your
distribution option at any time by writing the Fund at one of the
addresses on page 14 or calling 1-800-525-3713. The Fund offers
the following options:

1. REINVESTMENT OPTION. You may reinvest your income dividends
and capital gains distributions in additional shares. This
option is assigned automatically if no other choice is made.

2. CASH OPTION. You may receive your income dividends and capital
gains distributions in cash.

3. REINVEST AND CASH OPTION. You may receive either your income
dividends or capital gains distributions in cash and reinvest
the other in additional shares.

4. REDIRECT OPTION. You may direct your dividends or capital
gains to purchase shares of another Janus fund.

The Fund reserves the right to reinvest into your account
undeliverable and uncashed dividend and distribution checks that
remain outstanding for six months in shares of the Fund at the
NAV next computed after the check is cancelled. Subsequent
distributions may also be reinvested.

TAXES

As with any investment, you should consider the tax consequences
of investing in the Fund. Any time you sell or exchange shares of
a Fund in a taxable account, it is considered a taxable event.
Depending on the purchase price and the sale price, you may have
a gain or loss on the transaction. Any tax liabilities generated
by your transactions are your responsibility.

The following discussion does not apply to tax-deferred accounts,
nor is it a complete analysis of the federal tax implications of

Janus Fund prospectus 33
<PAGE>

investing in the Fund. You may wish to consult your own tax
adviser. Additionally, state or local taxes may apply to your
investment, depending upon the laws of your state of residence.

TAXES ON DISTRIBUTIONS

Dividends and distributions by the Fund are subject to federal
income tax, regardless of whether the distribution is made in
cash or reinvested in additional shares of the Fund.
Distributions may be taxable at different rates depending on the
length of time the Fund holds a security. In certain states, a
portion of the dividends and distributions (depending on the
source of the Fund's income) may be exempt from state and local
taxes. Information regarding the tax status of income dividends
and capital gains distributions will be mailed to shareholders on
or before January 31st of each year. Account tax information will
also be sent to the IRS.

TAXATION OF THE FUND

Dividends, interest, and some capital gains received by the Fund
on foreign securities may be subject to tax withholding or other
foreign taxes. The Fund 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 an election is not made, any foreign taxes paid or accrued
will represent an expense to the Fund.

The Fund does not expect to pay federal income or excise taxes
because it intends to meet certain requirements of the Internal
Revenue Code. It is important that the Fund meet these
requirements so that any earnings on your investment will not be
taxed twice.

34 Janus Fund prospectus
<PAGE>

FINANCIAL HIGHLIGHTS
- --------------------------------------------------------------------------------

The financial highlights table is intended to help you understand
the Fund's financial performance for the past 5 years through
October 31st of each fiscal year shown. Items 1 through 9 reflect
financial results for a single Fund share. The total returns in
the table represent the rate that an investor would have earned
(or lost) on an investment in the Fund (assuming reinvestment of
all dividends and distributions). This information has been
audited by PricewaterhouseCoopers LLP, whose report, along with
the Fund's financial statements, are included in the Annual
Report, which is available upon request and incorporated by
reference into the SAI.

Janus Fund prospectus 35
<PAGE>

JANUS FUND
<TABLE>
<CAPTION>
- -----------------------------------------------------------------------------------------
Periods ending October 31st
1999 1998 1997 1996 1995
<S> <C> <C> <C> <C> <C>
1. NET ASSET VALUE, BEGINNING OF
PERIOD $27.97 $29.36 $26.65 $23.37 $19.62
INCOME FROM INVESTMENT OPERATIONS:
2. Net investment income -- (0.02) 0.15 0.31 0.16
3. Net gains or losses on securities
(both realized and unrealized) 15.63 3.70 5.69 4.23 3.99
4. Total from investment operations 15.63 3.68 5.84 4.54 4.15
LESS DISTRIBUTIONS:
5. Dividends (from net investment
income) -- (0.23) (0.21) (0.13) (0.01)
6. Dividends (in excess of net
investment income) -- -- -- -- --
7. Distributions (from capital gains) (0.82) (4.84) (2.92) (1.13) (0.39)
8. Total distributions (0.82) (5.07) (3.13) (1.26) (0.40)
9. NET ASSET VALUE, END OF PERIOD $42.78 $27.97 $29.36 $26.65 $23.37
10. Total return 56.75% 15.12% 24.18% 20.31% 21.62%
11. Net assets, end of period (in
millions) $35,835 $20,721 $19,029 $15,313 $11,963
12. Average net assets for the period
(in millions) $28,993 $20,777 $17,515 $13,753 $10,560
13. Ratio of gross expenses to average
net assets 0.85% 0.87% 0.87% 0.86% 0.87%
14. Ratio of net expenses to average
net assets 0.84% 0.86% 0.86% 0.85% 0.86%
15. Ratio of net investment
income/(loss) to average net
assets (0.14%) -- 0.85% 0.91% 1.25%
16. Portfolio turnover rate 63% 70% 132% 104% 118%
- -----------------------------------------------------------------------------------------
</TABLE>

36 Janus Fund prospectus
<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 Fund may
invest. The Fund may invest in these instruments to the extent
permitted by its investment objective and policies. The Fund 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
Fund 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 stocks 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

Janus Fund prospectus 37
<PAGE>

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 Fund
must pay if these investments are profitable, the Fund may make

38 Janus Fund prospectus
<PAGE>

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

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
Fund and a simultaneous agreement by the seller (generally a bank
or dealer) to repurchase the security from the Fund 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 Fund 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 Fund to another party (generally a bank or dealer) in return
for cash and an agreement by the Fund to buy the security back at
a specified price and time. This technique will be used primarily
to provide cash to satisfy unusually heavy redemption requests,
or for other temporary or emergency purposes.

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

Janus Fund prospectus 39
<PAGE>

of the U.S. government to purchase the agency's obligations and
others are supported only by the credit of the sponsoring agency.

WARRANTS are securities, typically issued with preferred stocks
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
Fund does not earn interest on such securities until settlement
and bears 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.

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
Fund 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 Fund 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 Fund
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

40 Janus Fund prospectus
<PAGE>

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 instrument and may be more volatile
than the underlying instrument. The Fund bears the market risk of
an investment in the underlying instrument, as well as the credit
risk of the issuer.

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 Fund may purchase and
write put and call options on securities, securities indices and
foreign currencies.

Janus Fund prospectus 41
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[JANUS LOGO]

You can request other information, including a Statement of
Additional Information, Annual Report or Semiannual Report, free
of charge, by contacting Janus at 1-800-525-3713 or visiting our
Web site at janus.com. In the Fund's Annual Report, you will
find a discussion of the market conditions and investment
strategies that significantly affected the Fund's performance
during its last fiscal year. Other information is also available
from financial intermediaries that sell shares of the Fund.

The Statement of Additional Information provides detailed
information about the Fund and is incorporated into this
Prospectus by reference. You may review the Fund'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. 811-1879

1-800-525-3713
PO Box 173375 Denver, CO 80217-3375
janus.com
4239

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[JANUS LOGO]
JANUS MERCURY FUND
PROSPECTUS

JANUARY 31, 2000

<PAGE>

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<PAGE>

TABLE OF CONTENTS
- --------------------------------------------------------------------------------

<TABLE>
<S> <C>
RISK/RETURN SUMMARY
Janus Mercury Fund........................... 2
Fees and expenses............................ 4
INVESTMENT OBJECTIVE, PRINCIPAL INVESTMENT
STRATEGIES AND RISKS
Investment objective and principal investment
strategies................................... 5
General portfolio policies................... 6
Risks........................................ 9
SHAREHOLDER'S MANUAL
Minimum investments.......................... 15
Types of account ownership................... 15
To purchase shares........................... 18
To exchange shares........................... 19
To redeem shares............................. 19
Shareholder services and account policies.... 23
MANAGEMENT OF THE FUND
Investment adviser........................... 27
Portfolio manager............................ 28
Assistant portfolio managers................. 28
OTHER INFORMATION............... ............... 29
DISTRIBUTIONS AND TAXES
Distributions................................ 31
Taxes........................................ 32
FINANCIAL HIGHLIGHTS.............. ............. 34
GLOSSARY
Glossary of investment terms................. 36

</TABLE>

Janus Mercury Fund prospectus 1
<PAGE>

RISK/RETURN SUMMARY
- --------------------------------------------------------------------------------

JANUS MERCURY FUND

1. WHAT IS THE INVESTMENT OBJECTIVE OF JANUS MERCURY FUND?

The Fund seeks long-term growth of capital.

2. WHAT ARE THE MAIN INVESTMENT STRATEGIES OF JANUS MERCURY FUND?

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

The Fund may invest without limit in foreign equity and debt
securities and less than 35% of its net assets in
high-yield/high-risk bonds.

3. WHAT ARE THE MAIN RISKS OF INVESTING IN JANUS MERCURY FUND?

The value of the Fund's portfolio may decrease if the value of an
individual company in the portfolio decreases. The value of the
Fund's portfolio could also decrease if the stock market goes

2 Janus Mercury Fund prospectus
<PAGE>

down. If the value of the Fund's portfolio decreases, the Fund's
net asset value (NAV) will also decrease which means if you sell
your shares in the Fund you would get back less money.

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

JANUS MERCURY FUND

A BAR CHART showing Annual Total Returns for Janus Mercury Fund
from 1994 through 1999:

Annual returns for periods ended 12/31
<TABLE>
<S> <C> <C> <C> <C> <C> <C>
15.96% 33.01% 17.67% 11.88% 58.41% 96.23%
1994 1995 1996 1997 1998 1999

Each percentage is represented by a bar of proportionate size
with the actual total return printed above the bar.

Best Quarter: 4th-1999 42.72% Worst Quarter: 3rd-1998 (6.49%)
</TABLE>

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

<TABLE>
<CAPTION>
Since Inception
1 year 5 years (5/3/93)
<S> <C> <C> <C>
Janus Mercury Fund 96.23% 40.33% 35.46%
S&P 500 Index* 21.03% 28.54% 22.29%
--------------------------------------
</TABLE>

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

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

Janus Mercury Fund prospectus 3
<PAGE>

FEES AND EXPENSES

<TABLE>
<CAPTION>
Janus Mercury Fund
<S> <C>
Management Fee(1) 0.65%
Other Expenses 0.27%
Total Annual Fund Operating Expenses 0.92%
</TABLE>

<TABLE>
<CAPTION>
1 Year 3 Years 5 Years 10 Years
----------------------------------------
<S> <C> <C> <C> <C>
Janus Mercury Fund $94 $293 $509 $1,131
</TABLE>

4 Janus Mercury Fund prospectus
<PAGE>

INVESTMENT OBJECTIVES, PRINCIPAL INVESTMENT
STRATEGIES AND RISKS
- --------------------------------------------------------------------------------

INVESTMENT OBJECTIVE AND PRINCIPAL INVESTMENT STRATEGIES

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

Janus Mercury Fund prospectus 5
<PAGE>

invest and the Fund may at times have significant foreign
exposure.

GENERAL PORTFOLIO POLICIES

- debt securities

- indexed/structured securities

6 Janus Mercury Fund prospectus
<PAGE>

- high-yield/high-risk bonds (less than 35% of the Fund'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

Janus Mercury Fund prospectus 7
<PAGE>

a "special situation" investment does not occur or does not
attract the expected attention.

8 Janus Mercury Fund prospectus
<PAGE>

RISKS

Because the Fund 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 Fund's share price may
also decrease. The Fund'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 fund with a small asset base. A fund 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 Fund.

1. THE FUND 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.

Janus Mercury Fund prospectus 9
<PAGE>

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

- currency risk

- political and economic risk

- regulatory risk

- market risk

- transaction costs

These risks are described in the SAI.

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

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

4. HOW DOES THE FUND TRY TO REDUCE RISK?

The Fund 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 Fund may

10 Janus Mercury Fund prospectus
<PAGE>

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 Fund. However, the Fund's performance could be worse
than if the Fund 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.

5. I'VE HEARD A LOT ABOUT HOW THE CHANGE TO THE YEAR 2000 COULD AFFECT COMPUTER
SYSTEMS. DOES THIS CREATE ANY SPECIAL RISKS?

Janus Mercury Fund prospectus 11
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[JANUS LOGO]
JANUS MERCURY FUND
SHAREHOLDER'S MANUAL