MFS VARIABLE INSURANCE TRUST, 497, 2000-07-19

MFS VARIABLE INSURANCE TRUST
497, 2000-07-19

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INVESTMENT MANAGEMENT
We invented the mutual fund(RegTM)]

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MFS[RegTM] VARIABLE INSURANCE TRUST(SM)
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Prospectus
Initial Class

MAY 1, 2000

MFS[RegTM] EMERGING GROWTH SERIES
MFS[RegTM] CAPITAL OPPORTUNITIES SERIES
MFS[RegTM] GROWTH WITH INCOME SERIES
MFS[RegTM] GROWTH SERIES
MFS[RegTM] TOTAL RETURN SERIES

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

This Prospectus describes five series of the MFS Variable Insurance Trust
(referred to as the trust):

1. MFS Emerging Growth Series seeks to provide long-term growth of capital
(referred to as the Emerging Growth Series).

2. MFS Capital Opportunities Series seeks capital appreciation (referred to as
the Capital Opportunities Series).

3. MFS Growth With Income Series seeks to provide reasonable current income
and long-term growth of capital and income (referred to as the Growth With
Income Series).

4. MFS Growth Series seeks to provide long-term growth of capital and future
income rather than current income (referred to as the Growth Series).

5. MFS Total Return Series seeks mainly to provide above-average income
(compared to a portfolio invested entirely in equity securities)
consistent with the prudent employment of capital, and secondarily to
provide a reasonable opportunity for growth of capital and income
(referred to as the Total Return Series).

The Securities and Exchange Commission has not approved the series' shares or
determined whether this prospectus is accurate or complete. Anyone who tells
you otherwise is committing a crime.
<PAGE>

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

<TABLE>
<CAPTION>
Page
<S> <C> <C>
I Expense Summary ............................................ (1)

II Risk Return Summary ........................................ (3)

1. Emerging Growth Series ................................. (3)

2. Capital Opportunities Series ........................... (6)

3. Growth With Income Series .............................. (9)

4. Growth Series .......................................... (11)

5. Total Return Series .................................... (13)

III Certain Investment Strategies and Risks .................... (17)

IV Management of the Series ................................... (17)

V Description of Shares ...................................... (18)

VI Other Information .......................................... (18)

VII Financial Highlights ....................................... (19)

Appendix A -- Investment Techniques and Practices .......... (A-1)
</TABLE>

<PAGE>

The trust offers shares of its 16 series to separate accounts established by
insurance companies in order to serve as investment vehicles for variable
annuity and variable life insurance contracts and to qualified pension and
retirement plans. Each of these series is managed by Massachusetts Financial
Services Company (referred to as MFS or the adviser). Five of these are
described below.

--------------------
I EXPENSE SUMMARY
--------------------

(>) Expense Table

This table describes the expense that you may pay when you hold initial
class shares of the series. These fees and expenses do not take into account
the fees and expenses imposed by insurance companies through which your
investment in a series may be made.

Annual Series Operating Expenses (expenses that are deducted from a series'
assets):

<TABLE>
<CAPTION>
Growth
Emerging Capital With Total
Growth Opportunities Income Return
Series Series Series Growth Series Series
---------- --------------- -------- ------------- ---------
<S> <C> <C> <C> <C> <C>
Management Fee ................................. 0.75% 0.75% 0.75% 0.75% 0.75%
Other Expenses(1) .............................. 0.09% 0.27% 0.13% 0.71% 0.15%
---- ---- ---- ---- ----
Total Annual Series Operating Expenses ......... 0.84% 1.02% 0.88% 1.46% 0.90%
Expense Reimbursement ......................... N/A (0.11)%(2) N/A (0.55)%(2) N/A
---- ---- ---- ---- ----
Net Expenses(1) ............................... 0.84% 0.91% 0.88% 0.91% 0.90%
</TABLE>

-------------
(1) Each series has an expense offset arrangement which reduces the series'
custodian fee based upon the amount of cash maintained by the series
with its custodian and dividend disbursing agent. Each series may enter
into other such arrangements and directed brokerage arrangements, which
would also have the effect of reducing the series' expenses. "Other
Expenses" do not take into account these expense reductions, and are
therefore higher than the actual expenses of the series. Had these fee
reductions been taken into account, "Net Expenses" would be lower for
certain series and would equal:
0.83% for Emerging Growth Series 0.90% for Growth Series
0.90% for Capital Opportunities Series 0.89% for Total Return Series
0.87% for Growth with Income Series

(2) MFS has contractually agreed, subject to reimbursement, to bear expenses
for these series such that each such series' "Other Expenses" (after
taking into account the expense offset arrangement described above), do
not exceed 0.15% for Capital Opportunities Series and 0.15% for Growth
Series of the average daily net assets of the series during the current
fiscal year. These contractual fee arrangements will continue until at
least May 1, 2001, unless changed with the consent of the board of
trustees which oversees the series.

1
<PAGE>

(>) Example of Expenses--Initial Class

These examples are intended to help you compare the cost of investing in the
series with the cost of investing in other mutual funds. These examples do
not take into account the fees and expenses imposed by insurance companies
through which your investment in a series may be made.

The examples assume that:

o You invest $10,000 in the series for the time periods indicated and you
redeem your shares at the end of the time periods;

o Your investment has a 5% return each year and dividends and other
distributions are reinvested; and

o The series' operating expenses remain the same, except that the series'
total operating expenses are assumed to be the series' "Net Expenses"
for the first year, and the series' "Total Annual Series Operating
Expenses" for subsequent years (see the expense table on the previous
page).

Although your actual costs may be higher or lower, under these assumptions
your costs would be:

<TABLE>
<CAPTION>
Period
------------------------------------------
Series 1 Year 3 Years 5 Years 10 Years
----------------------------------------------------------------------------
<S> <C> <C> <C> <C>
Emerging Growth Series $86 $268 $466 $1,037
Capital Opportunities Series 93 314 553 1,238
Growth With Income Series 90 281 488 1,084
Growth Series 93 408 745 1,699
Total Return Series 92 287 498 1,108
</TABLE>

2
<PAGE>

------------------------
II RISK RETURN SUMMARY
------------------------

Investment strategies which are common to all series are described under the
caption "Certain Investment Strategies."

1: Emerging Growth Series
...........................................................................

(>) Investment Objective

The series' investment objective is long term growth of capital. The series'
objective may be changed without shareholder approval.

(>) Principal Investment Policies

The series invests, under normal market conditions, at least 65% of its
total assets in common stocks and related securities, such as preferred
stocks, convertible securities and depositary receipts for those securities,
of emerging growth companies. Emerging growth companies are companies which
MFS believes are either:

o early in their life cycle but which have the potential to become major
enterprises, or

o major enterprises whose rates of earnings growth are expected to
accelerate because of special factors, such as rejuvenated management,
new products, changes in consumer demand, or basic changes in the
economic environment.

Emerging growth companies may be of any size, and MFS would expect these
companies to have products, technologies, management, markets and
opportunities which will facilitate earnings growth over time that is well
above the growth rate of the overall economy and the rate of inflation. The
series' investments may include securities listed on a securities exchange
or traded in the over-the-counter (OTC) markets.

MFS uses a bottom-up, as opposed to a top-down, investment style in managing
the equity-oriented funds (such as the series) it advises. This means that
securities are selected based upon fundamental analysis (such as an analysis
of earnings, cash flows, competitive position and management's abilities)
performed by the series' portfolio manager and MFS' large group of equity
research analysts.

The series may invest in foreign securities (including emerging market
securities), through which it may have exposure to foreign currencies.

The series has engaged and may engage in active and frequent trading to
achieve its principal investment strategies.

(>) Principal Risks of an Investment

The principal risks of investing in the series and the circumstances
reasonably likely to cause the value of your investment in the series to
decline are described below. The share price of the series generally changes
daily based on market conditions and other factors. Please note that there
are many circumstances which could cause the value of your investment in the
series to decline, and which could prevent the series from achieving its
objective, that are not described here.

The principal risks of investing in the series are:

o Market Risk: This is the risk that the price of a security held by the
series will fall due to changing economic, political or market
conditions or disappointing earnings results.

o Emerging Growth Risk: Prices of securities react to the economic
condition of the company that issued the security. The series' equity
investments in an issuer may rise and fall based on the issuer's actual
and anticipated earnings, changes in management and the potential for
takeovers and acquisitions. Investments in emerging growth companies may
be subject to more abrupt or erratic market movements and may involve
greater risks than investments in other companies. Emerging growth
companies often:

> have limited product lines, markets and financial resources

> are dependent on management by one or a few key individuals

> have shares which suffer steeper than average price declines
after disappointing earnings reports and are more difficult to
sell at satisfactory prices

o Over-the-Counter Risk: OTC transactions involve risks in addition to
those associated with transactions in securities traded on exchanges.
OTC-listed companies may have limited product lines, markets or
financial resources. Many OTC stocks trade less frequently and in
smaller volume than exchange-listed stocks. The values of these stocks
may be more volatile than exchange-listed stocks, and the series may
experience difficulty in establishing or closing out positions in these
stocks at prevailing market prices.

3
<PAGE>

o Foreign Securities Risk: Investments in foreign securities involve risks
relating to political, social and economic developments abroad, as well
as risks resulting from the differences between the regulations to which
U.S. and foreign issuers and markets are subject:

> These risks may include the seizure by the government of company
assets, excessive taxation, withholding taxes on dividends and
interest, limitations on the use or transfer of portfolio
assets, and political or social instability.

> Enforcing legal rights may be difficult, costly and slow in
foreign countries, and there may be special problems enforcing
claims against foreign governments.

> Foreign companies may not be subject to accounting standards or
governmental supervision comparable to U.S. companies, and there
may be less public information about their operations.

> Foreign markets may be less liquid and more volatile than U.S.
markets.

> Foreign securities often trade in currencies other than the U.S.
dollar, and the series may directly hold foreign currencies and
purchase and sell foreign currencies through forward exchange
contracts. Changes in currency exchange rates will affect the
series' net asset value, the value of dividends and interest
earned, and gains and losses realized on the sale of securities.
An increase in the strength of the U.S. dollar relative to these
other currencies may cause the value of the series to decline.
Certain foreign currencies may be particularly volatile, and
foreign governments may intervene in the currency markets,
causing a decline in value or liquidity in the series' foreign
currency holdings. By entering into forward foreign currency
exchange contracts, the series may be required to forego the
benefits of advantageous changes in exchange rates and, in the
case of forward contracts entered into for the purpose of
increasing return, the series may sustain losses which will
reduce its gross income. Forward foreign currency exchange
contracts involve the risk that the party with which the series
enters the contract may fail to perform its obligations to the
series.

o Emerging Markets Risk: Emerging markets are generally defined as
countries in the initial stages of their industrialization cycles with
low per capita income. Investments in emerging markets securities
involve all of the risks of investments in foreign securities, and also
have additional risks:

> All of the risks of investing in foreign securities are
heightened by investing in emerging markets countries.

> The markets of emerging markets countries have been more
volatile than the markets of developed countries with more
mature economies. These markets often have provided
significantly higher or lower rates of return than developed
markets, and significantly greater risks, to investors.

o Active or Frequent Trading Risk: The fund has engaged and may engage in
active and frequent trading to achieve its principal investment
strategies. This may result in the realization and distribution to
shareholders of higher capital gains as compared to a fund with less
active trading policies. Frequent trading also increases transaction
costs, which could detract from the fund's performance.

o As with any mutual fund, you could lose money on your investment in the
series.

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

(>) Bar Chart and Performance Table

The bar chart and performance table below are intended to indicate some of
the risks of investing in the series by showing changes in the series'
performance over time. The performance table also shows how the series
performance over time compares with that of one or more broad measures of
market performance. The chart and table provide past performance information
based on calendar year periods. The series' past performance does not
necessarily indicate how the series will perform in the future. The returns
shown do not reflect fees and charges imposed under the variable annuity and
life insurance contracts through which an investment may be made. If these
fees and charges were included, they would reduce these returns.

4
<PAGE>

Bar Chart

The bar chart shows changes in the annual total returns of the series'
initial class, assuming the reinvestment of distributions.

[Bar chart data]

[End bar chart]

During the period shown in the bar chart, the highest quarterly return was
55.05% (for the calendar quarter ended December 31, 1999) and the lowest
quarterly return was (13.11)% (for the calendar quarter ended September 30,
1998).

Performance Table

This table shows how the average annual total returns of the series' shares
compares to a broad measure of market performance and various other market
indicators and assumes the reinvestment of distributions.

Average Annual Total Returns as of December 31, 1999
............................................................................

<TABLE>
<CAPTION>
1 Year Life*
<S> <C> <C>
Emerging Growth Series--Initial Class 76.71% 36.44%
Russell 2000 Total Return Index**+ 21.26% 14.06%
Standard & Poor's 500 Composite Index**++ 21.04% 26.53%
</TABLE>

-------------
* Series performance figures are for the period from the commencement of
the series' investment operations, July 24, 1995, through December 31,
1999. Index returns are from August 1, 1995.

** Source: Standard & Poor's Micropal, Inc.

+ The Russell 2000 Total Return Index is a broad-based, unmanaged index
comprised of 2,000 of the smallest U.S.-domiciled company common stocks
(on the basis of capitalization) that are traded in the United States on
the New York Stock Exchange (NYSE), the American Stock Exchange (AMEX),
and NASDAQ.

++ The Standard & Poor's 500 Composite Index is a broad-based, unmanaged,
but commonly used measure of common stock total return performance. It
is comprised of 500 widely held common stocks listed on the NYSE, AMEX
and over-the-counter market.

(>) Portfolio Manager

Toni Y. Shimura, a Senior Vice President of the Adviser, has been employed
in the investment management area of the Adviser since 1987. Ms. Shimura
became portfolio manager of the series on November 30, 1995. John W. Ballen,
Chief Investment Officer and President of MFS, provides general oversight in
the management of the series' portfolio.

5
<PAGE>

2: Capital Opportunities Serie
............................................................................

(>) Investment Objective

The series' investment objective is capital appreciation. The series'
objective may be changed without shareholder approval.

(>) Principal Investment Policies

The series invests, under normal market conditions, at least 65% of its
total assets in common stocks and related securities, such as preferred
stocks, convertible securities and depositary receipts for those securities.
The series focuses on companies which MFS believes have favorable growth
prospectus and attractive valuations based on current and expected earnings
or cash flow. The series' investments may include securities listed on a
securities exchange or traded in the over-the-counter markets.

The series may invest in foreign securities (including emerging market
securities), through which it may have exposure to foreign currencies.

The series has engaged and may engage in active and frequent trading to
achieve its principal investment strategies.

(>) Principal Risks of an Investment

The principal risks of investing in the series are:

o Market Risk: This is the risk that the price of a security held by the
series will fall due to changing economic, political or market
conditions or disappointing earnings results.

o Company Risk: Prices of securities react to the economic condition of
the company that issued the security. The series' equity investments in
an issuer may rise and fall based on the issuer's actual and anticipated
earnings, changes in management and the potential for takeovers and
acquisitions.

o Over-the-Counter Risk: Over-the-counter (OTC) transactions involve risks
in addition to those associated with transactions in securities traded
on exchanges. OTC-listed companies may have limited product lines,
markets or financial resources. Many OTC stocks trade less frequently
and in smaller volume than exchange-listed stocks. The values of these
stocks may be more volatile than exchange-listed stocks, and the series
may experience difficulty in establishing or closing out positions in
these stocks at prevailing market prices.

> Enforcing legal rights may be difficult, costly and slow in
foreign countries, and there may be special problems enforcing
claims against foreign governments.

> Foreign companies may not be subject to accounting standards or
governmental supervision comparable to U.S. companies, and there
may be less public information about their operations.

> Foreign markets may be less liquid and more volatile than U.S.
markets.

6
<PAGE>

By entering into forward foreign currency exchange contracts,
the series may be required to forego the benefits of
advantageous changes in exchange rates and, in the case of
forward contracts entered into for the purpose of increasing
return, the series may sustain losses which will reduce its
gross income. Forward foreign currency exchange contracts
involve the risk that the party with which the series enters the
contract may fail to perform its obligations to the series.

> All of the risks of investing in foreign securities are
heightened by investing in emerging markets countries.

o Active or Frequent Trading Risk: The series has engaged and may engage
in active and frequent trading to achieve its principal investment
strategies. This may result in the realization and distribution to
shareholders of higher capital gains as compared to a series with less
active trading policies. Frequent trading also increases transaction
costs, which could detract from the series' performance.

o As with any mutual fund, you could lose money on your investment in the
series.

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

(>) Bar Chart and Performance Table

Bar Chart

The bar chart shows changes in the annual total returns of the series'
initial class, assuming the reinvestment of distributions.

[Bar chart data]

[End bar chart]

During the period shown in the bar chart, the highest quarterly return was
27.90% (for the calendar quarter ended December 31, 1999) and the lowest
quarterly return was (13.91)% (for the calendar quarter ended September 30,
1998).

7
<PAGE>

Performance Table

Average Annual Total Returns as of December 31, 1999
............................................................................

<TABLE>
<CAPTION>
1 Year Life*
<S> <C> <C>
Capital Opportunities Series--Initial Class 47.42% 32.23%
Standard & Poor's 500 Composite Index**+++ 21.04% 29.60%
Average capital appreciation fund++ 41.65% 24.03%
</TABLE>

-------------
* Series performance figures are for the period from the commencement of
the series' investment operations on August 14, 1996, through December
31, 1999. Index and Lipper average returns are from August 1, 1996.

++ Source: Lipper Inc.

+++ Source: Standard and Poor's Micropal, Inc.

** The Standard & Poor's 500 Composite Index is a broad-based, unmanaged
index of common stock total return performance. It is comprised of 500
widely held common stocks listed on the New York Stock Exchange (NYSE),
American Stock Exchange (AMEX) and over-the-counter (OTC) market. The
investment return and principal value of stocks fluctuate with changes
in market conditions. It is not possible to invest directly in an index.

(>) Portfolio Manager

Maura A. Shaughnessy, a Senior Vice President of the Adviser, has been
employed in the investment management area of the Adviser since 1991. Ms.
Shaughnessy has been the series' portfolio manager since February 24, 1999.

8
<PAGE>

3: Growth With Income Series
............................................................................

(>) Investment Objective

The series' investment objective is to provide reasonable current income and
long-term growth of capital and income. The series' objective may be changed
without shareholder approval.

(>) Principal Investment Policies

The series invests, under normal market conditions, at least 65% of its
total assets in common stocks and related securities, such as preferred
stocks, convertible securities and depositary receipts for those securities.
These securities may be listed on a securities exchange or traded in the
over-the-counter markets. While the series may invest in companies of any
size, the series generally focuses on companies with larger market
capitalizations that MFS believes have sustainable growth prospects and
attractive valuations based on current and expected earnings or cash flow.
The series will also seek to generate gross income equal to approximately
90% of the dividend yield on the Standard & Poor's 500 Composite Index.

The series may invest in foreign equity securities through which it may have
exposure to foreign currencies.

(>) Principal Risks of an Investment

The principal risks of investing in the series are:

o Market Risk: This is the risk that the price of a security held by the
series will fall due to changing economic, political or market
conditions or disappointing earnings results.

o Large Cap Companies Risk: Large cap companies tend to go in and out of
favor based on market and economic conditions. Large cap companies tend
to be less volatile than companies with smaller market capitalizations.
In exchange for this potentially lower risk, the series' value may not
rise as much as the value of series that emphasize smaller cap
companies.

o Foreign Securities Risk: Investing in foreign securities involves risks
relating to political, social and economic developments abroad, as well
as risks resulting from the differences between the regulations to which
U.S. and foreign issuers and markets are subject:

> Enforcing legal rights may be difficult, costly and slow in
foreign countries, and there may be special problems enforcing
claims against foreign governments.

> Foreign companies may not be subject to accounting standards or
governmental supervision comparable to U.S. companies, and there
may be less public information about their operations.

> Foreign markets may be less liquid and more volatile than U.S.
markets.

9
<PAGE>

the series' foreign currency holdings. By entering into forward
foreign currency exchange contracts, the series may be required
to forego the benefits of advantageous changes in exchange rates
and, in the case of forward contracts entered into for the
purpose of increasing return, the series may sustain losses
which will reduce its gross income. Forward foreign currency
exchange contracts involve the risk that the party with which
the series enters the contract may fail to perform its
obligations to the series.

o As with any mutual fund, you could lose money on your investment in the
series.

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

(>) Bar Chart and Performance Table

The bar chart and performance table below are intended to indicate some of
the risks of investing in the series by showing changes in the series'
performance over time. The performance table also shows how the series
performance over time compares with that of a broad measure of market
performance. The chart and table provide past performance information based
on calendar year periods. The series' past performance does not necessarily
indicate how the series will perform in the future. The returns shown do not
reflect fees and charges imposed under the variable annuity and life
insurance contracts through which an investment may be made. If these fees
and charges were included, they would reduce these returns.

Bar Chart

The bar chart shows changes in the annual total returns of the series'
initial class, assuming the reinvestment of distributions.

[Bar chart data]

[End bar chart]

During the period shown in the bar chart, the highest quarterly return was
18.29% (for the calendar quarter ended December 31, 1998) and the lowest
quarterly return was (10.95)% (for the calendar quarter ended September 30,
1998).

Performance Table

This table shows how the average annual total returns of the series' shares
compares to a broad measure of market performance and assumes the
reinvestment of distributions.

Average Annual Total Returns as of December 31, 1999
............................................................................

<TABLE>
<CAPTION>
1 Year Life*
<S> <C> <C>
Growth With Income Series--Initial Class 6.69% 21.12%
Standard & Poor's 500 Composite Index**++ 21.04% 26.39%
</TABLE>

-------------
* Series performance figures are for the period from the commencement of
the series' investment operations on October 9, 1995, through December
31, 1999. Index returns are from October 1, 1995.

++ Source: Standard & Poor's Micropal, Inc.

** The Standard & Poor's 500 Composite Index is a broad-based, unmanaged
but commonly used measure of common stock total return performance. It
is comprised of 500 widely held common stocks listed on the NYSE, AMEX
and OTC market. The investment return and principal value of stocks
fluctuate with changes in market conditions. It is not possible to
invest directly in an index.

(>) Portfolio Manager

John D. Laupheimer, a Senior Vice President of the Adviser, has been
employed in the investment management area of the Adviser since 1981. Mr.
Laupheimer has been the series' portfolio manager since its inception.
Mitchell D. Dynan, a Senior Vice President of the Adviser, has been employed
in the investment management area of the Adviser since 1986. Mr. Dynan has
been the series' portfolio manager since May 1, 1999.

10
<PAGE>

4: Growth Series
............................................................................

(>) Investment Objective

The series' investment objective is to provide long-term growth of capital
and future income rather than current income. The series' objective may be
changed without shareholder approval.

(>) Principal Investment Policies

The series invests, under normal market conditions, at least 80% of its
total assets in common stocks and related securities, such as preferred
stocks, convertible securities and depositary receipts for those securities,
of companies which MFS believes offer better than average prospects for
long-term growth.

In managing the series, MFS seeks to purchase securities of companies which
MFS considers well-run and poised for growth. MFS looks particularly for
companies which demonstrate:

o a strong franchise, strong cash flows and a recurring revenue stream

o a strong industry position, where there is

> potential for high profit margins

> substantial barriers to new entry in the industry

o a strong management with a clearly defined strategy, and

o new products or services

The series may invest in foreign securities through which it may have
exposure to foreign currencies.

(>) Principal Risks of an Investment

The principal risks of investing in the series are:

o Market Risk: This is the risk that the price of a security held by the
series will fall due to changing economic, political or market
conditions or disappointing earnings results.

o Growth Companies Risk: Prices of growth company securities held by the
series may fall to a greater extent than the overall equity markets
(e.g., as represented by the Standard and Poor's Composite 500 Index)
due to changing economic, political or market conditions or
disappointing growth company earnings results.

> Enforcing legal rights may be difficult, costly and slow in
foreign countries, and there may be special problems enforcing
claims against foreign governments.

11
<PAGE>

> Foreign companies may not be subject to accounting standards or
governmental supervision comparable to U.S. companies, and there
may be less public information about their operations.

> Foreign markets may be less liquid and more volatile than U.S.
markets.

o As with any mutual fund, you could lose money on your investment in the
series.

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

(>) Bar Chart and Performance Table

The bar chart and performance table are not included because the series had
not commenced investment operations as of December 31, 1998 and therefore
did not have a full calendar year of operations at December 31, 1999.

(>) Portfolio Manager

Stephen Pesek and Thomas D. Barrett are the portfolio managers of the
series. Mr. Pesek, a Senior Vice President of the Adviser, has been a
portfolio manager of the series since its inception and has been employed in
the investment management area of the Adviser since 1994. Mr. Barrett, a
Vice President of the Adviser, became a portfolio manager of the series on
May 1, 2000. Mr. Barrett has been employed in the investment management area
of the Adviser since 1996. Prior to joining MFS in 1996, Mr. Barrett had
been an Assistant Vice President and Equity Research Analyst with The Boston
Company Asset Management, Inc.

12
<PAGE>

5: Total Return Series
............................................................................

(>) Investment Objectives

The series' main investment objective is to provide above-average income
(compared to a portfolio invested entirely in equity securities) consistent
with the prudent employment of capital. Its secondary objective is to
provide reasonable opportunity for growth of capital and income. The series'
objectives may be changed without shareholder approval.

(>) Principal Investment Policies

The series is a "balanced fund," and invests in a combination of equity and
fixed income securities. Under normal market conditions, the series invests:

o at least 40%, but not more than 75%, of its net assets in common stocks
and related securities (referred to as equity securities), such as
preferred stock; bonds, warrants or rights convertible into stock; and
depositary receipts for those securities, and

o at least 25% of its net assets in non-convertible fixed income
securities.

The series may vary the percentage of its assets invested in any one type of
security (within the limits described above) in accordance with MFS's
interpretation of economic and money market conditions, fiscal and monetary
policy and underlying security values.

Consistent with the series' principal investment policies the series may
invest in foreign securities, and may have exposure to foreign currencies
through its investment in these securities.

The series has engaged and may engage in active and frequent trading to
achieve its principal investment strategies.

Equity Investments. While the series may invest in all types of equity
securities, MFS generally seeks to purchase for the series equity
securities, such as common stocks, preferred stocks, convertible securities
and depositary receipts, of companies that MFS believes are undervalued in
the market relative to their long-term potential. The equity securities of
these companies may be undervalued because:

o they are viewed by MFS as being temporarily out of favor in the market
due to

> a decline in the market,

> poor economic conditions,

> developments that have affected or may affect the issuer of the
securities or the issuer's industry, or

o the market has overlooked them.

Undervalued equity securities generally have low price-to-book,
price-to-sales and/or price-to-earnings ratios. The series focuses on
undervalued equity securities issued by companies with relatively large
market capitalizations (i.e., market capitalizations of $5 billion or more).

As noted above, the series' investments in equity securities include
convertible securities. A convertible security is a security that may be
converted within a specified period of time into a certain amount of common
stock of the same or a different issuer. A convertible security generally
provides:

o a fixed income stream, and

o the opportunity, through its conversion feature, to participate in an
increase in the market price of the underlying common stock.

MFS uses a bottom-up, as opposed to a top-down, investment style in managing
the equity-oriented funds (including the equity portion of the series) it
advises. This means that securities are selected based upon fundamental
analysis (such as an analysis of earnings, cash flows, competitive position
and management's abilities) performed by the series' portfolio manager and
MFS' large group of equity research analysts.

Fixed Income Investments. The series invests in securities which pay a fixed
interest rate, which include:

o U.S. government securities, which are bonds or other debt obligations
issued by, or whose principal and interest payments are guaranteed or
supported by, the U.S. government or one of its agencies or
instrumentalities,

o mortgage-backed and asset-backed securities, which represent interests
in a pool of assets such as mortgage loans, car loan receivables, or
credit card receivables. These investments entitle the series to a share
of the principal and interest payments made on the underlying mortgage,
car loan, or credit card. For example, if the series invests in a pool
that includes your mortgage loan, a share of the principal and interest
payments on your mortgage would pass to the series, and

o corporate bonds, which are bonds or other debt obligations issued by
corporations or other similar entities.

13
<PAGE>

In selecting fixed income investments for the series, MFS considers the
views of its large group of fixed income portfolio managers and research
analysts. This group periodically assesses the three-month total return
outlook for various segments of the fixed income markets. This three-month
"horizon" outlook is used by the portfolio manager(s) of MFS' fixed-income
oriented series (including the fixed-income portion of the series) as a tool
in making or adjusting a series' asset allocations to various segments of
the fixed income markets. In assessing the credit quality of fixed-income
securities, MFS does not rely solely on the credit ratings assigned by
credit rating agencies, but rather performs its own independent credit
analysis.

(>) Principal Risks of an Investment

The principal risks of investing in the series are:

o Allocation Risk: The series will allocate its investments between equity
and fixed income securities, and among various segments of the fixed
income markets, based upon judgments made by MFS. The series could miss
attractive investment opportunities by underweighting markets where
there are significant returns, and could lose value by overweighting
markets where there are significant declines.

> Enforcing legal rights may be difficult, costly and slow in
foreign countries, and there may be special problems enforcing
claims against foreign governments.

> Foreign companies may not be subject to accounting standards or
governmental supervision comparable to U.S. companies, and there
may be less public information about their operations.

> Foreign markets may be less liquid and more volatile than U.S.
markets.

o Market Risk: This is the risk that the price of a security held by the
series will fall due to changing economic, political or market
conditions or disappointing earnings results.

o Undervalued Securities Risk: Prices of securities react to the economic
condition of the company that issued the security. The series' equity
investments in an issuer may rise and fall based on the issuer's actual
and anticipated earnings, changes in management and the potential for
takeovers and acquisitions. MFS will invest in securities that are
undervalued based on its belief that the market value of these
securities will rise due to anticipated events and investor perceptions.
If these events do not occur or are delayed, or if investor perceptions
about the securities do not improve, the market price of these
securities may not rise or may fall.

o Interest Rate Risk: When interest rates rise, the prices of fixed income
securities in the series' portfolio will generally fall. Conversely,
when interest rates fall, the prices of fixed income securities in the
series' portfolio will generally rise.

o Convertible Securities Risk: Convertible securities, like fixed income
securities, tend to increase in value when interest rates decline and
decrease in value when interest rates rise. The market value of a
convertible security also tends to increase as the market value of the
underlying stock rises and decrease as the market value of the
underlying stock declines.

14
<PAGE>

o Maturity Risk: Interest rate risk will generally affect the price of a
fixed income security more if the security has a longer maturity. Fixed
income securities with longer maturities will therefore be more volatile
than other fixed income securities with shorter maturities. Conversely,
fixed income securities with shorter maturities will be less volatile
but generally provide lower returns than fixed income securities with
longer maturities. The average maturity of the series' fixed income
investments will affect the volatility of the series' share price.

o Credit Risk: Credit risk is the risk that the issuer of a fixed income
security will not be able to pay principal and interest when due. Rating
agencies assign credit ratings to certain fixed income securities to
indicate their credit risk. The price of a fixed income security will
generally fall if the issuer defaults on its obligation to pay principal
or interest, the rating agencies downgrade the issuer's credit rating or
other news affects the market's perception of the issuer's credit risk.

o Liquidity Risk: The fixed income securities purchased by the series may
be traded in the over-the-counter market rather than on an organized
exchange and are subject to liquidity risk. This means that they may be
harder to purchase or sell at a fair price. The inability to purchase or
sell these fixed income securities at a fair price could have a negative
impact on the series' performance.

o Mortgage and Asset-Backed Securities:

> Maturity Risk:

+ Mortgage-Backed Securities: A mortgage-backed security will
mature when all the mortgages in the pool mature or are
prepaid. Therefore, mortgage-backed securities do not have a
fixed maturity, and their expected maturities may vary when
interest rates rise or fall.

[plus] When interest rates fall, homeowners are more likely to
prepay their mortgage loans. An increased rate of
prepayments on the series' mortgage-backed securities
will result in an unforeseen loss of interest income to
the series as the series may be required to reinvest
assets at a lower interest rate. Because prepayments
increase when interest rates fall, the prices of
mortgage-backed securities does not increase as much as
other fixed income securities when interest rates fall.

[plus] When interest rates rise, homeowners are less likely to
prepay their mortgage loans. A decreased rate of
prepayments lengthens the expected maturity of a
mortgage-backed security. Therefore, the prices of
mortgage-backed securities may decrease more than prices
of other fixed income securities when interest rates
rise.

+ Collateralized Mortgage Obligations: The series may invest
in mortgage-backed securities called collateralized mortgage
obligations (CMOs). CMOs are issued in separate classes with
different stated maturities. As the mortgage pool
experiences prepayments, the pool pays off investors in
classes with shorter maturities first. By investing in CMOs,
the series may manage the prepayment risk of mortgage-backed
securities. However, prepayments may cause the actual
maturity of a CMO to be substantially shorter than its
stated maturity.

+ Asset-Backed Securities: Asset-backed securities have
prepayment risks similar to mortgage-backed securities.

> Credit Risk: As with any fixed income security, mortgage-backed
and asset-backed securities are subject to the risk that the
issuer will default on principal and interest payments. It may
be difficult to enforce rights against the assets underlying
mortgage-backed and asset-backed securities in the case of
default. The U.S. government or its agencies may guarantee the
payment of principal and interest on some mortgage-backed
securities. Mortgage-backed securities and asset-backed
securities issued by private lending institutions or other
financial intermediaries may be supported by insurance or other
forms of guarantees.

o As with any mutual fund, you could lose money on your investment in the
series.

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

(>) Bar Chart and Performance Table

15
<PAGE>

Bar Chart

The bar chart shows changes in the annual total returns of the series'
initial class, assuming the reinvestment of distributions.

[Bar chart data]

[End bar chart]

During the period shown in the bar chart, the highest quarterly return was
9.86% (for the calendar quarter ended June 30, 1997) and the lowest
quarterly return was (4.64)% (for the calendar quarter ended September 30,
1999).

Performance Table

This table shows how the average annual total returns of the series' shares
compares to broad measures of market performance and various other market
indicators and assumes the reinvestment of distributions.

Average Annual Total Returns as of December 31, 1999
............................................................................

<TABLE>
<CAPTION>
1 Year Life*
<S> <C> <C>
Total Return Series--Initial Class 3.08% 15.42%
Standard & Poor's 500 Composite Index**+ 21.04% 28.56%
Lipper Balanced Index#++ 9.00% 16.33%
Lehman Brothers Government/Corporate Bond Index**+++ (2.15)% 7.61%
Lipper average balanced fund# 8.72% 16.24%
</TABLE>

--------------
* Series performance figures are for the period from the commencement of
the series' investment operations, January 3, 1995, through December 31,
1999. Index and Lipper average returns are from January 1, 1995.

** Source: Standard & Poor's Micropal, Inc.

# Source: Lipper Inc.

+ The Standard & Poor's 500 Composite Index is a broad-based, unmanaged
but commonly used measure of common stock total return performance. It
is composed of 500 widely held common stocks listed on the NYSE, AMEX
and OTC market.

++ The Lipper Balanced Index is a broad based, unmanaged,
net-asset-value-weighted index of the largest qualifying mutual funds in
this Lipper category adjusted for the reinvestment of capital gain
distributions and income.

+++ The Lehman Brothers Government/Corporate Bond Index is a broad-based,
unmanaged, market-value-weighted index of all debt obligations of the
U.S. Treasury and government-agency securities (excluding
mortgage-backed securities) and of all publicly issued fixed-rate,
nonconvertible, investment-grade domestic corporate debt.

(>) Portfolio Manager

David M. Calabro, a Senior Vice President of MFS, has been employed in the
investment management area of the Adviser since 1992. Mr. Calabro is the
head of the series' portfolio management team and a manager of the common
stock portion of the series' portfolio. Geoffrey L. Kurinsky, a Senior Vice
President of MFS, has been employed in the investment management area of the
Adviser since 1987. Mr. Kurinsky is the manager of the series' fixed income
securities. Constantinos G. Mokas, a Vice President of MFS, has been a
portfolio manager of the series since April 1, 1998, and has been employed
in the investment management area of the Adviser since 1990. Mr. Mokas is
the manager of the series' convertible securities. Lisa B. Nurme, a Senior
Vice President of MFS, has been a portfolio manager of the series since July
19, 1995, and has been employed in the investment management area of the
Adviser since 1987. Ms. Nurme is a manager of the common stock portion of
the series' portfolio. Kenneth J. Enright, a Senior Vice President of MFS,
has been employed in the investment management area of the Adviser since
1986 and has been a portfolio manager of the series since January 15, 1999.
Mr. Enright is a manager of the common stock portion of the series'
portfolio.

16
<PAGE>

--------------------------------------------
III CERTAIN INVESTMENT STRATEGIES AND RISKS
--------------------------------------------

(>) Further Information on Investment Strategies and Risks

Each series may invest in various types of securities and engage in various
investment techniques and practices which are not the principal focus of the
series and therefore are not described in this prospectus. The types of
securities and investment techniques and practices in which a series may
engage, including the principal investment techniques and practices
described above, are identified in Appendix A to this Prospectus, and are
discussed, together with their risks, in the trust's Statement of Additional
Information (referred to as the SAI), which you may obtain by contacting MFS
Service Center, Inc. (see back cover for address and phone number).

(>) Temporary Defensive Policies

Each series may depart from its principal investment strategies by
temporarily investing for defensive purposes when adverse market, economic
or political conditions exist. While a series invests defensively, it may
not be able to pursue its investment objective. A series defensive
investment position may not be effective in protecting its value.

(>) Active or Frequent Trading

Each series may engage in active and frequent trading to achieve its
principal investment strategies. This may result in the realization and
distribution to shareholders of higher capital gains as compared to a series
with less active trading policies. Frequent trading also increases
transaction costs, which could detract from the series' performance.

-----------------------------
IV MANAGEMENT OF THE SERIES
-----------------------------

(>) Investment Adviser

Massachusetts Financial Services Company (referred to as MFS or the adviser)
is the investment adviser to each series. MFS is America's oldest mutual
fund organization. MFS and its predecessor organizations have a history of
money management dating from 1924 and the founding of the first mutual fund,
Massachusetts Investors Trust. Net assets under the management of the MFS
organization were approximately $136.7 billion as of December 31, 1999. MFS
is located at 500 Boylston Street, Boston, Massachusetts 02116.

MFS provides investment management and related administrative services and
facilities to each series, including portfolio management and trade
execution. For these services, each series pays MFS an annual management fee
as set forth in the Expense Summary.

MFS or its affiliates generally pay an administrative service fee to
insurance companies which use the series as underlying investment vehicles
for their variable annuity and variable life insurance contracts based upon
the aggregate net assets of the series attributable to these contracts.
These fees are not paid by the series, their shareholders, or by the
contract holders.

(>) Administrator

MFS provides each series with certain financial, legal, compliance,
shareholder communications and other administrative services. MFS is
reimbursed by each series for a portion of the costs it incurs in providing
these services.

(>) Distributor

MFS Fund Distributors, Inc. (referred to as MFD), a wholly owned subsidiary
of MFS, is the distributor of shares of the series.

(>) Shareholder Servicing Agent

MFS Service Center, Inc. (referred to as MFSC), a wholly owned subsidiary of
MFS, performs transfer agency and certain other services for each series,
for which it receives compensation from each series.

17
<PAGE>

--------------------------
V DESCRIPTION OF SHARES
--------------------------

The trust offers two classes of shares--initial class shares and service
class shares. Initial class shares are offered through this prospectus.
Service class shares, which bear a Rule 12b-1 distribution fee, are
available through a separate prospectus supplement. These shares are offered
to separate accounts established by insurance companies in order to serve as
investment vehicles for variable annuity and variable life insurance
contracts. The trust also offers shares of each of its series to qualified
pension and retirement plans. All purchases, redemptions and exchanges of
shares are made through these insurance company separate accounts and plans,
which are the record owner of the shares. Contract holders and plan
beneficiaries seeking to purchase, redeem or exchange interests in the
trust's shares should consult with the insurance company which issued their
contracts or their plan sponsor.

----------------------
VI OTHER INFORMATION
----------------------

(>) Pricing of Series' Shares

The price of each series' shares is based on its net asset value. The net
asset value of each series' shares is determined at the close of regular
trading each day that the New York Stock Exchange is open for trading
(generally, 4:00 p.m., Eastern time) (referred to as the valuation time).
The New York Stock Exchange is closed on most national holidays and Good
Friday. To determine net asset value, each series values its assets at
current market values, or at fair value as determined by the Adviser under
the direction of the Board of Trustees that oversees the series if current
market values are unavailable. Fair value pricing may be used by a series
when current market values are unavailable or when an event occurs after the
close of the exchange on which the series' portfolio securities are
principally traded that is likely to have changed the value of the
securities. The use of fair value pricing by a series may cause the net
asset value of its shares to differ significantly from the net asset value
that would be calculated using current market values.

Insurance companies and plan sponsors are the designees of the trust for
receipt of purchase, exchange and redemption orders from contractholders and
plan beneficiaries. An order submitted to the trust's designee by the
valuation time will receive the net asset value next calculated; provided
that the trust receives notice of the order generally by 9:30 a.m. eastern
time on the next day on which the New York Stock Exchange is open for
trading.

Certain series invest in securities which are primarily listed on foreign
exchanges that trade on weekends and other days when the series does not
price its shares. Therefore, the value of these series' shares may change on
days when you will not be able to purchase or redeem their shares.

(>) Distributions

Each series intends to pay substantially all of its net income (including
any realized net capital and net foreign currency gains) to shareholders as
dividends at least annually.

(>) Tax Considerations

The following discussion is very general. You are urged to consult your tax
adviser regarding the effect that an investment in a series may have on your
tax situation. Each series of the Trust is treated as a separate corporation
for federal tax purposes. As long as a series qualifies for treatment as a
regulated investment company (which each series has done in the past and
which each series intends to do in the future), it pays no federal income
tax on the earnings it distributes to shareholders. In addition, each series
also intends to continue to diversify its assets to satisfy the federal
diversification tax rules applicable to separate accounts that fund variable
insurance and annuity contracts.

Shares of the series are offered to insurance company separate accounts and
to qualified retirement and pension plans. You should consult with the
insurance company that issued your contract to understand the federal tax
treatment of your investment.

(>) Right to Reject or Restrict Purchase and Exchange Orders

Purchases and exchanges should be made for investment purposes only. Each
series reserves the right to reject or restrict any specific purchase or
exchange request. Because an exchange request involves both a request to
redeem shares of one series and to purchase shares of another series, the
series consider the underlying redemption and purchase requests conditioned
upon the acceptance of each of these underlying requests. Therefore, in the
event that the series reject an exchange request, neither the redemption nor
the purchase side of the exchange will be processed. When a series
determines that the level of exchanges on any day may be harmful to its
remaining shareholders, the

18
<PAGE>

series may delay the payment of exchange proceeds for up to seven days to
permit cash to be raised through the orderly liquidation of its portfolio
securities to pay the redemption proceeds. In this case, the purchase side
of the exchange will be delayed until the exchange proceeds are paid by the
redeeming series.

(>) Excessive Trading Practices

The series do not permit market-timing or other excessive trading practices.
Excessive, short-term (market-timing) trading practices may disrupt
portfolio management strategies and harm series' performance. As noted
above, each series reserves the right to reject or restrict any purchase
order (including exchanges) from any investor. To minimize harm to the
series and their shareholders, the series will exercise these rights if an
investor has a history of excessive trading or if an investor's trading, in
the judgment of the series, has been or may be disruptive to a series. In
making this judgment, the series may consider trading done in multiple
accounts under common ownership or control.

(>) In-kind distributions

The series have reserved the right to pay redemption proceeds by a
distribution in-kind of portfolio securities (rather than cash). In the
event that the series makes an in-kind distribution, you could incur the
brokerage and transaction charges when converting the securities to cash.
The series do not expect to make in-kind distributions.

(>) Unique Nature of Series

MFS may serve as the investment adviser to other funds which have investment
goals and principal investment policies and risks similar to those of the
series, and which may be managed by the series' portfolio manager(s). While
a series may have many similarities to these other funds, its investment
performance will differ from their investment performance. This is due to a
number of differences between a series and these similar products, including
differences in sales charges, expense ratios and cash flows.

(>) Potential Conflicts

Shares of the series are offered to the separate accounts of insurance
companies that may be affiliated or unaffiliated with MFS and each other
("shared funding") and may serve as the underlying investments for both
variable annuity and variable life insurance contracts ("mixed funding").
Due to differences in tax treatment or other considerations, the interests
of various contract owners might at some time be in conflict. The trust
currently does not foresee any such conflict. Nevertheless, the board of
trustees which oversees the series intends to monitor events in order to
identify any material irreconcilable conflicts which may possibly arise and
to determine what action, if any, should be taken in response. If such a
conflict were to occur, one or more separate accounts of the insurance
companies might be required to withdraw its investments in one or more
series. This might force a series to sell securities at disadvantageous
prices.

-------------------------
VII FINANCIAL HIGHLIGHTS
-------------------------

The financial highlights table is intended to help you understand the
series' financial performance for the past five years, or, if a series has
not been in operation that long, since the time it commenced investment
operations. Certain information reflects financial results for a single
series' share. The total returns in the table represent the rate by which an
investor would have earned (or lost) on an investment in a series (assuming
reinvestment of all distributions). This information has been audited by the
trust's independent auditors, whose report, together with the trust's
financial statements, are included in the trust's Annual Report to
shareholders. The series' Annual Report is available upon request by
contacting MFSC (see back cover for address and telephone number). These
financial statements are incorporated by reference into the SAI. The trust's
independent auditors are Deloitte & Touche LLP.

19
<PAGE>

1. Emerging Growth Series--Initial Class
................................................................................

<TABLE>
<CAPTION>
Year Ended December 31, Period Ended
----------------------------------------------- December 31,
1999 1998 1997 1996 1995*
------------------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C> <C>
Per share data (for a share outstanding throughout
each period):
Net asset value -- beginning of period ............... $ 21.47 $ 16.13 $ 13.24 $ 11.41 $10.00
---------- -------- -------- -------- ------
Income from investment operations# --
Net investment income (loss)[sec] ................... $ (0.06) $ (0.05) $ (0.06) $ (0.01) $ 0.01
Net realized and unrealized gain on investments and
foreign currency transactions ...................... 16.53 5.55 2.95 1.95 1.74
---------- -------- -------- -------- ------
Total from investment operations .................. $ 16.47 $ 5.50 $ 2.89 $ 1.94 $ 1.75
---------- -------- -------- -------- ------
Less distributions declared to shareholders --
From net investment income .......................... $ -- $ -- $ -- $ -- $(0.01)
From net realized gain on investments and foreign
currency transactions .............................. -- (0.05) -- (0.06) (0.26)
In excess of net realized gain on investments and
foreign currency transactions ...................... -- (0.11) -- (0.05) --
From paid-in capital ................................ -- -- -- -- (0.07)
---------- -------- -------- -------- ------
Total distributions declared to shareholders ...... $ -- $ (0.16) $ -- $ (0.11) $(0.34)
---------- -------- -------- -------- ------
Net asset value -- end of period ..................... $ 37.94 $ 21.47 $ 16.13 $ 13.24 $11.41
---------- -------- -------- -------- ------
Total return ......................................... 76.71% 34.16% 21.90% 17.02% 17.41%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .......................................... 0.84% 0.85% 0.90% 1.00% 1.00%+
Net investment income (loss) ........................ (0.23)% (0.29)% (0.38)% (0.08)% 0.10%+
Portfolio turnover ................................... 176% 71% 112% 96% 73%
Net assets at end of period (000 omitted) ............ $2,132,528 $908,987 $384,480 $104,956 $3,869

[sec] Prior to January 1, 1998, the investment adviser voluntarily agreed to maintain, subject to reimbursement by the
Series, the expenses of the Series at not more than 1.00% of average daily net assets. To the extent actual expenses
were over or under this limitation, the net investment loss per share and the ratios would have been:

Net investment loss ................................ $(0.05) $(0.03) $(0.18)
Ratios (to average net assets):
Expenses## ........................................ 0.87% 1.16% 2.91%+
Net investment loss ............................... (0.35)% (0.23)% (1.78)%+
</TABLE>

-------------
* For the period from the commencement of the Series' investment operations,
July 24, 1995, through December 31, 1995.

+ Annualized.

++ Not annualized.

# Per share data are based on average shares outstanding.

## Ratios do not reflect expense reductions from certain offset arrangements.

20
<PAGE>

2. Capital Opportunities Series--Initial Class
................................................................................

<TABLE>
<CAPTION>
Year Ended December 31,
------------------------------------------
1999 1998 1997 1996*
---------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C>
Per share data (for a share outstanding throughout
each period):
Net asset value -- beginning of period ............... $ 14.79 $ 11.68 $10.66 $10.00
------- ------- ------ ------
Income from investment operations# --
Net investment income (loss)[sec] ................... $ (0.02) $ 0.03 $ 0.12 $ 0.07
Net realized and unrealized gain on investments and
foreign currency ................................... 7.02 3.11 2.66 0.88
------- ------- ------ ------
Total from investment operations .................. $ 7.00 $ 3.14 $ 2.78 $ 0.95
------- ------- ------ ------
Less distributions declared to shareholders --
From net investment income .......................... $ -- $ (0.02) $(0.09) $(0.03)
From net realized gain on investments and foreign
currency transactions .............................. (0.05) (0.01) (1.54) (0.21)
In excess of net realized gain on investments and
foreign currency transactions ...................... -- -- -- (0.01)
From capital ........................................ -- -- (0.13) (0.04)
------- ------- ------ ------
Total distributions declared to shareholders ...... $ (0.05) $ (0.03) $(1.76) $(0.29)
------- ------- ------ ------
Net asset value -- end of period ..................... $ 21.74 $ 14.79 $11.68 $10.66
------- ------- ------ ------
Total return ......................................... 47.42% 26.80% 26.47% 8.78%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .......................................... 1.02% 1.02% 1.02% 1.02%+
Net investment income (loss) ........................ (0.13)% 0.21% 0.91% 1.72%+
Portfolio turnover ................................... 152% 144% 270% 44%
Net assets at end of period (000 omitted) ............ $63,172 $23,908 $5,660 $1,351

[sec] Subject to reimbursement by the Series, MFS has voluntarily agreed under a temporary expense
reimbursement agreement to pay all the Series' operating expenses, exclusive of management
fees. In consideration, the Series pays MFS a fee not greater than 0.25% of average daily net
assets. To the extent actual expenses were over this limitation, the net investment income
(loss) per share and the ratios would have been:

Net investment income (loss) ....................... $(0.02) $0.02 $(0.02) $(0.04)
Ratios (to average net assets):
Expenses## ........................................ 1.03 1.11% 2.08% 3.83%+
Net investment income (loss) ...................... (0.15)% 0.12% (0.18)% (1.11)%+
</TABLE>

---------
* For the period from the commencement of the Series' investment operations,
August 14, 1996, through December 31, 1996.

+ Annualized.

++ Not annualized.

# Per share data are based on average shares outstanding.

## Ratios do not reflect expense reductions from certain expense offset
arrangements.

21
<PAGE>

3. Growth With Income Series--Initial Class
................................................................................

<TABLE>
<CAPTION>
Year Ended December 31, Period Ended
------------------------------------------- December 31,
1999 1998 1997 1996 1995*
-------------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C> <C>
Per share data (for a share outstanding throughout
each period):
Net asset value -- beginning of period ............... $ 20.11 $ 16.44 $ 12.98 $10.61 $ 10.00
-------- -------- ------- ------ -------
Income from investment operations# --
Net investment income[sec] .......................... $ 0.12 $ 0.13 $ 0.16 $ 0.18 $ 0.05
Net realized and unrealized gain on investments and
foreign currency ................................... 1.22 3.54 3.70 2.42 0.61
-------- -------- ------- ------ -------
Total from investment operations .................. $ 1.34 $ 3.67 $ 3.86 $ 2.60 $ 0.66
-------- -------- ------- ------ -------
Less distributions declared to shareholders --
From net investment income .......................... $ (0.06) $ -- $ (0.07) $(0.09) $ (0.05)
From net realized gain on investments and foreign
currency transactions .............................. (0.08) -- (0.29) (0.13) --
In excess of net realized gain on investments and
foreign currency transactions ...................... -- -- (0.04) (0.01) --
-------- -------- ------- ------ -------
Total distributions declared to shareholders ...... $ (0.14) $ -- $ (0.40) $(0.23) $ (0.05)
-------- -------- ------- ------ -------
Net asset value -- end of period ..................... $ 21.31 $ 20.11 $ 16.44 $12.98 $ 10.61
-------- -------- ------- ------ -------
Total return ......................................... 6.69% 22.32% 29.78% 24.46% 6.64%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .......................................... 0.88% 0.95% 1.00% 1.01% 1.00%+
Net investment income ............................... 0.56% 0.73% 0.93% 1.52% 2.20%+
Portfolio turnover ................................... 72% 57% 42% 41% 2%
Net assets at end of period (000 omitted) ............ $390,762 $244,310 $58,045 $9,174 $ 365

[sec] Prior to October 2, 1998, subject to reimbursement by the Series, MFS voluntarily agreed under a temporary
expense reimbursement agreement to pay all the Series' operating expenses, exclusive of management fee. In
consideration, the Series paid MFS a fee not greater than 0.25% of average daily net assets. To the extent
actual expenses were over/under this limitation, the net investment income (loss) per share and the ratios
would have been:

Net investment income (loss) ....................... -- $0.14 $0.13 $0.05 $(0.41)
Ratios (to average net assets):
Expenses## ........................................ -- 0.88% 1.10% 2.07% 21.44%+
Net investment income (loss) ...................... -- 0.80% 0.82% 0.46% (18.24)%+
</TABLE>

-------------
* For the period from the commencement of the Series' investment operations,
October 9, 1995, through December 31, 1995.

+ Annualized.

++ Not annualized.

# Per share data are based on average shares outstanding.

## Ratios do not reflect expense reductions from certain expense offset
arrangements.

22
<PAGE>

4. Growth Series--Initial Class
................................................................................

<TABLE>
<CAPTION>
Period Ended
December 31,1999*
-------------------------------------------------------------------------------------------
<S> <C>
Per share data (for a share outstanding throughout the period):
Net asset value -- beginning of period .................................. $ 10.00
-------
Income from investment operations# --
Net investment income[sec] ............................................. $ 0.06
Net realized and unrealized gain on investments and foreign currency ... 3.94
-------
Total from investment operations ..................................... $ 4.00
-------
Less distributions declared to shareholders
From net investment income ............................................. $ (0.02)
From net realized gain on investments and foreign currency transactions (0.03)
-------
Total distributions declared to shareholders ......................... $ (0.05)
-------
Net asset value -- end of period ........................................ $ 13.95
-------
Total return ............................................................ 40.01%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## ............................................................. 1.01%+
Net investment income .................................................. 0.71%+
Portfolio turnover ...................................................... 73%
Net assets at end of period (000 omitted) ............................... $18,889

[sec] Subject to reimbursement by the Series, MFS has voluntarily agreed under a
temporary expense reimbursement agreement to pay all of the Series' operating
expenses, exclusive of management fee. In consideration, the Series pays MFS a
reimbursement fee not greater than 0.25% of average daily net assets. To the
extent actual expenses were over this limitation, the net investment income per
share and ratios would have been:

Net investment income ................................................. $ 0.02++
Ratios (to average net assets):
Expenses## ........................................................... 1.47%+
Net investment income ................................................ 0.25%+
</TABLE>

-------------
* For the period from the commencement of the Series' investment operations,
May 3, 1999, through December 31, 1999.

+ Annualized.

++ Not annualized.

# Per share data are based on average shares outstanding.

## Ratios do not reflect expense reductions from certain expense offset
arrangements.

23
<PAGE>

5. Total Return Series--Initial Class
................................................................................

<TABLE>
<CAPTION>
Year Ended December 31, Period Ended
-------------------------------------------- December 31,
1999 1998 1997 1996 1995*
------------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C> <C>
Per share data (for a share outstanding throughout
each period):

Net asset value -- beginning of period ............... $ 18.12 $ 16.63 $ 13.71 $ 12.25 $10.00
-------- -------- ------- ------- ------
Income from investment operations# --
Net investment income[sec] .......................... $ 0.53 $ 0.53 $ 0.52 $ 0.46 $ 0.41
Net realized and unrealized gain on investments and
foreign currency ................................... 0.05 1.49 2.40 1.30 2.32
-------- -------- ------- ------- ------
Total from investment operations .................. $ 0.58 $ 2.02 $ 2.92 $ 1.76 $ 2.73
-------- -------- ------- ------- ------
Less distributions declared to shareholders --
From net investment income .......................... $ (0.33) $ (0.24) $ -- $ (0.21) $(0.25)
From net realized gain on investments and foreign
currency transactions .............................. (0.62) (0.29) -- (0.09) (0.23)
-------- -------- ------- ------- ------
Total distributions declared to shareholders ...... $ (0.95) $ (0.53) $ -- $ (0.30) $(0.48)
-------- -------- ------- ------- ------
Net asset value -- end of period ..................... $ 17.75 $ 18.12 $ 16.63 $ 13.71 $12.25
-------- -------- ------- ------- ------
Total return ......................................... 3.08% 12.33% 21.30% 14.37% 27.34%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .......................................... 0.90% 1.00% 1.00% 1.00% 1.00%+
Net investment income ............................... 2.97% 3.05% 3.25% 3.59% 3.83%+
Portfolio turnover ................................... 112% 100% 93% 76% 16%
Net assets at end of period (000 omitted) ............ $256,128 $171,182 $75,612 $19,250 $2,797

[sec] Subject to reimbursement by the Series, the investment adviser voluntarily agreed under a temporary expense
reimbursement agreement to maintain the expenses of the Series, exclusive of management fees, at not more
than 0.25% of average daily net assets for certain of the periods indicated. To the extent actual expenses
were over/under this limitation, the net investment income per share and the ratios would have been:

Net investment income .............................. -- $0.54 $0.52 $0.32 $0.22
Ratios (to average net assets):
Expenses## ........................................ -- 0.91% 1.02% 2.10% 2.49%+
Net investment income ............................. -- 3.14% 3.23% 2.49% 2.09%+
</TABLE>

-------------
* For the period from the commencement of the Series' investment operations,
January 3, 1995, through December 31, 1995.

+ Annualized.

++ Not annualized.

# Per share data are based on average shares outstanding.

## Ratios do not reflect expense reductions from certain expense offset
arrangements.

24
<PAGE>

------------------- ------------------------------------------
A p p e n d i x A E m e r g i n g G r o w t h S e r i e s
------------------- ------------------------------------------

(>) Investment Techniques and Practices

In pursuing its investment objective and investment policies, the Emerging
Growth Series may engage in the following principal and non- principal
investment techniques and practices. Investment techniques and practices
which are the principal focus of the series are also described, together
with their risks, in the Risk Return Summary of the Prospectus. Both
principal and non-principal investment techniques and practices are
described, together with their risks, in the SAI.

<TABLE>
<CAPTION>
Symbols X permitted -- not permitted
-------------------------------------------------------------------
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclass
Pass-Through Securities --
Corporate Asset-Backed Securities --
Mortgage Pass-Through Securities --
Stripped Mortgage-Backed Securities --
Corporate Securities X
Loans and Other Direct Indebtedness --
Lower Rated Bonds X
Municipal Bonds --
Speculative Bonds X
U.S. Government Securities X
Variable and Floating Rate Obligations X
Zero Coupon Bonds, Deferred Interest Bonds
and PIK Bonds X
Equity Securities X
Foreign Securities Exposure
Brady Bonds --
Depositary Receipts X
Dollar-Denominated Foreign Debt Securities --
Emerging Markets X
Foreign Securities X
Forward Contracts X
Futures Contracts X
Indexed Securities/Structured Products --
Inverse Floating Rate Obligations --
Investment in Other Investment Companies
Open-End Funds X
Closed-End Funds X
Lending of Portfolio Securities X
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions --*
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies X
Options on Futures Contracts X
Options on Securities X
Options on Stock Indices X
Reset Options --
"Yield Curve" Options --
Repurchase Agreements X
Restricted Securities X
Short Sales --
Short Sales Against the Box --
Short Term Instruments X
Swaps and Related Derivative Instruments --
Temporary Borrowings X
Temporary Defensive Positions X
Warrants X
"When-Issued" Securities X
</TABLE>

*May be changed only with shareholder approval.

A-1
<PAGE>

------------------- ------------------------------------------------------
A p p e n d i x A C a p i t a l O p p o r t u n i t i e s S e r i e s
------------------- ------------------------------------------------------

(>) Investment Techniques and Practices

In pursuing its investment objective and investment policies, the Capital
Opportunities Series may engage in the following principal and non-principal
investment techniques and practices. Investment techniques and practices
which are the principal focus of the series are also described, together
with their risks, in the Risk Return Summary of the Prospectus. Both
principal and non-principal investment techniques and practices are
described, together with their risks, in the SAI.

<TABLE>
<CAPTION>
Symbols X permitted -- not permitted
-------------------------------------------------------------------
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclass
Pass-Through Securities --
Corporate Asset-Backed Securities --
Mortgage Pass-Through Securities --
Stripped Mortgage-Backed Securities --
Corporate Securities X
Loans and Other Direct Indebtedness --
Lower Rated Bonds X
Municipal Bonds --
Speculative Bonds X
U.S. Government Securities X
Variable and Floating Rate Obligations X
Zero Coupon Bonds, Deferred Interest Bonds and PIK Bonds X
Equity Securities X
Foreign Securities Exposure
Brady Bonds X
Depositary Receipts X
Dollar-Denominated Foreign Debt Securities --
Emerging Markets X
Foreign Securities X
Forward Contracts X
Futures Contracts X
Indexed Securities/Structured Products --
Inverse Floating Rate Obligations --
Investment in Other Investment Companies
Open-End Funds X
Closed-End Funds X
Lending of Portfolio Securities X
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions --*
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies X
Options on Futures Contracts X
Options on Securities X
Options on Stock Indices X
Reset Options --
"Yield Curve" Options --
Repurchase Agreements X
Restricted Securities X
Short Sales --
Short Sales Against the Box X
Short Term Instruments X
Swaps and Related Derivative Instruments --
Temporary Borrowings X
Temporary Defensive Positions X
Warrants X
"When-Issued" Securities X
</TABLE>

*May be changed only with shareholder approval.

A-2
<PAGE>

------------------- -----------------------------------------------
A p p e n d i x A G r o w t h W i t h I n c o m e S e r i e s
------------------- -----------------------------------------------

(>) Investment Techniques and Practices

In pursuing its investment objective and investment policies, the Growth
With Income Series may engage in the following principal and non-principal
investment techniques and practices. Investment techniques and practices
which are the principal focus of the series are also described, together
with their risks, in the Risk Return Summary of the Prospectus. Both
principal and non-principal investment techniques and practices are
described, together with their risks, in the SAI.

<TABLE>
<CAPTION>
Symbols X permitted -- not permitted
-------------------------------------------------------------------
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclass
Pass-Through Securities --
Corporate Asset-Backed Securities --
Mortgage Pass-Through Securities --
Stripped Mortgage-Backed Securities --
Corporate Securities X
Loans and Other Direct Indebtedness --
Lower Rated Bonds --
Municipal Bonds --
Speculative Bonds --
U.S. Government Securities --
Variable and Floating Rate Obligations X
Zero Coupon Bonds, Deferred Interest Bonds and PIK Bonds X
Equity Securities X
Foreign Securities Exposure
Brady Bonds --
Depositary Receipts X
Dollar-Denominated Foreign Debt Securities --
Emerging Markets X
Foreign Securities X
Forward Contracts X
Futures Contracts X
Indexed Securities/Structured Products --
Inverse Floating Rate Obligations --
Investment in Other Investment Companies
Open-End X
Closed-End X
Lending of Portfolio Securities X
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions --*
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies --
Options on Futures Contracts --
Options on Securities --
Options on Stock Indices --
Reset Options --
"Yield Curve" Options --
Repurchase Agreements X
Restricted Securities X
Short Sales --
Short Sales Against the Box X
Short Term Instruments X
Swaps and Related Derivative Instruments --
Temporary Borrowings X
Temporary Defensive Positions X
Warrants X
"When-Issued" Securities X
</TABLE>

*May be changed only with shareholder approval.

A-3
<PAGE>

------------------- -------------------------
A p p e n d i x A G r o w t h S e r i e s
------------------- -------------------------

(>) Investment Techniques and Practices

In pursuing its investment objective and investment policies, the Growth
Series may engage in the following principal and non-principal investment
techniques and practices. Investment techniques and practices which are the
principal focus of the series are also described, together with their risks,
in the Risk Return Summary of the Prospectus. Both principal and
non-principal investment techniques and practices are described, together
with their risks, in the SAI.

<TABLE>
<CAPTION>
Symbols X permitted -- not permitted
-------------------------------------------------------------------
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclass
Pass-Through Securities --
Corporate Asset-Backed Securities --
Mortgage Pass-Through Securities --
Stripped Mortgage-Backed Securities --
Corporate Securities --
Loans and Other Direct Indebtedness
Lower Rated Bonds --
Municipal Bonds --
Speculative Bonds --
U.S. Government Securities --
Variable and Floating Rate Obligations X
Zero Coupon Bonds, Deferred Interest Bonds and PIK Bonds --
Equity Securities X
Foreign Securities Exposure
Brady Bonds --
Depositary Receipts X
Dollar-Denominated Foreign Debt Securities --
Emerging Markets X
Foreign Securities X
Forward Contracts X
Futures Contracts X
Indexed Securities/Structured Products --
Inverse Floating Rate Obligations --
Investment in Other Investment Companies
Open-End Funds X
Closed-End Funds X
Lending of Portfolio Securities X
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions --*
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies X
Options on Futures Contracts X
Options on Securities X
Options on Stock Indices X
Reset Options --
"Yield Curve" Options --
Repurchase Agreements X
Restricted Securities X
Short Sales --
Short Sales Against the Box --
Short Term Instruments X
Swaps and Related Derivative Instruments --
Temporary Borrowing X
Temporary Defensive Positions X
Warrants --
"When-Issued" Securities X
</TABLE>

*May be changed only with shareholder approval.

A-4
<PAGE>

------------------- ------------------------------------
A p p e n d i x A T o t a l R e t u r n S e r i e s
------------------- ------------------------------------

(>) Investment Techniques and Practices

In pursuing its investment objective and investment policies, the Total
Return Series may engage in the following principal and non-principal
investment techniques and practices. Investment techniques and practices
which are the principal focus of the series are also described, together
with their risks, in the Risk Return Summary of the Prospectus. Both
principal and non-principal investment techniques and practices are
described, together with their risks, in the SAI.

<TABLE>
<CAPTION>
Symbols X permitted -- not permitted
-------------------------------------------------------------------
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclass
Pass-Through Securities X
Corporate Asset-Backed Securities X
Mortgage Pass-Through Securities X
Stripped Mortgage-Backed Securities X
Corporate Securities X
Loans and Other Direct Indebtedness X
Lower Rated Bonds X
Municipal Bonds X
Speculative Bonds X
U.S. Government Securities X
Variable and Floating Rate Obligations X
Zero Coupon Bonds, Deferred Interest Bonds and PIK Bonds X
Equity Securities X
Foreign Securities Exposure
Brady Bonds X
Depositary Receipts X
Dollar-Denominated Foreign Debt Securities X
Emerging Markets X
Foreign Securities X
Forward Contracts X
Futures Contracts X
Indexed Securities/Structured Products X
Inverse Floating Rate Obligations X
Investment in Other Investment Companies
Open-End Funds X
Closed-End Funds X
Lending of Portfolio Securities X
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions --*
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies X
Options on Futures Contracts X
Options on Securities X
Options on Stock Indices X
Reset Options X
"Yield Curve" Options X
Repurchase Agreements X
Restricted Securities X
Short Sales --
Short Sales Against the Box --
Short Term Instruments X
Swaps and Related Derivative Instruments X
Temporary Borrowings X
Temporary Defensive Positions X
Warrants X
"When-Issued" Securities X
</TABLE>

*May be changed only with shareholder approval.

A-5
<PAGE>

MFS[RegTM] VARIABLE INSURANCE TRUST(SM)

If you want more information about the trust and its series, the following
documents are available free upon request:

Annual/Semiannual Reports. These reports contain information about the
series' actual investments. Annual reports discuss the effect of recent
market conditions and the series' investment strategy on the series'
performance during its last fiscal year.

Statement of Additional Information (SAI). The SAI, dated May 1, 2000,
provides more detailed information about the trust and its series and is
incorporated into this prospectus by reference.

You can get free copies of the annual/semiannual reports, the SAI and other
information about the trust and its series, and make inquiries about the
trust and its series, by contacting:

MFS Service Center, Inc.
2 Avenue de Lafayette
Boston, MA 02111-1738
Telephone: 1-800-343-2829, ext. 3500
Internet: http://www.mfs.com

Information about the trust and its series (including its prospectus, SAI
and shareholder reports) can be reviewed and copied at the:

Public Reference Room
Securities and Exchange Commission
Washington, D.C., 20549-0102

Information on the operation of the Public Reference Room may be obtained by
calling the Commission at 202-942-8090. Reports and other information about
the trust and its series are available on the EDGAR Databases on the
Commission's Internet website at http://www.sec.gov, and copies of this
information may be obtained, upon payment of a duplicating fee, by
electronic request at the following E-mail address: [email protected], or
by writing the Public Reference Section at the above address.

The trust's Investment Company Act file number is 811-8326

MSG 11/98 224M 90/290/390/890