MFS VARIABLE INSURANCE TRUST, 497, 2000-02-02

MFS VARIABLE INSURANCE TRUST
497, 2000-02-02

Previous: AK STEEL HOLDING CORP, SC 13G/A, 2000-02-02

Next: TRIPLE S PLASTICS INC, SC 13G/A, 2000-02-02

[MFS LOGO[

----------------------------------
MFS(R) VARIABLE INSURANCE TRUST SM
----------------------------------

MAY 1, 1999 Prospectus

MFS(R) EMERGING GROWTH SERIES
MFS(R) RESEARCH SERIES
MFS(R) GROWTH WITH INCOME SERIES
MFS(R) TOTAL RETURN SERIES
- --------------------------------------------------------------------------------
This Prospectus describes four of the 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 Research Series seeks to provide long-term growth of capital and future
income (referred to as the Research 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); and

4. MFS Total Return Series seeks primarily 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>
<CAPTION>
- ------------------ Page
TABLE OF CONTENTS
- -----------------
<S> <C> <C>
I Expense Summary ............................................ 1

II Risk Return Summary ........................................ 2
1. Emerging Growth Series .................................. 2
2. Research Series ......................................... 4
3. Growth With Income Series ............................... 6
4. Total Return Series ..................................... 8

III Certain Investment Strategies and Risks .................... 12

IV Management of the Series ................................... 12

V Description of Shares ...................................... 12

VI Other Information .......................................... 13

VII Financial Highlights ....................................... 14
Appendix A -- Investment Techniques and Practices .......... A-1
</TABLE>

<PAGE>

The trust offers shares of its 15 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). Four of these series are described below.

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

> Expense Table
This table describes the expense that you may pay when you hold 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 With Total
Growth Research Income Return
Series Series Series Series
---------- ---------- ---------- ----------
<S> <C> <C> <C> <C>
Management Fee .................................... 0.75% 0.75% 0.75% 0.75%
Other Expenses(1) ................................. 0.10% 0.11% 0.13% 0.16%
---- ---- ---- ----
Total Annual Series Operating Expenses(1) ......... 0.85% 0.86% 0.88% 0.91%
Expense Reimbursement ............................ -- -- -- --
---- ---- ---- ----
Net Expenses(1) .................................. 0.85% 0.86% 0.88% 0.91%
</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. Expenses do not
take into account these expense reductions, and are therefore higher than
the actual expenses of the series.

> Example of Expenses

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.

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 $ 87 $ 271 $ 471 $ 1,049
Research Series 88 274 477 1,061
Growth With Income Series 90 281 488 1,084
Total Return Series 93 290 504 1,120
</TABLE>

1
<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 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
performed by the series' portfolio manager and MFS' large group of equity
research analysts.

> Principal Risks

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. As with any non-money market mutual fund, the
share price of the series will change 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: 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.

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.

2
<PAGE>

> 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.
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'
shares for each calendar year since they were first offered, assuming the
reinvestment of distributions.

[BAR CHART PLOT POINTS]

1996 17.02%
1997 21.90%
1998 34.16%

[END PLOT POINTS]

During the period shown in the bar chart, the highest quarterly return was
27.04% (for the calendar quarter ended December 31, 1998) 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, 1998
.............................................................................

<TABLE>
<CAPTION>
1 Year Life
<S> <C> <C>
Emerging Growth Series* 34.16% +26.55%
Russell 2000 Total Return Index**+ -2.55% +12.03%
Standard & Poor's 500 Composite Index**++ +28.58% +28.16%
</TABLE>

---------
* "Life" refers to the period from the commencement of the series'
investment operations, July 24, 1995, through December 31, 1998.
** Source: CDA/Wiesenberger. "Life" refers to the period from
August 1, 1995, through December 31, 1998.
+ 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, the American Stock Exchange,
and Nasdaq.
++ The Standard & Poor's 500 Composite Index is a broad based, unmanaged
index of common stock total return performance.

> Portfolio Manager

John W. Ballen, President of MFS, has been employed by the Adviser as a
portfolio manager since 1984. Mr. Ballen has been the series' portfolio
manager since its inception. Toni Y. Shimura, a Vice President of MFS, has
been employed by the Adviser as a portfolio manager since 1987. Ms. Shimura
became portfolio manager of the series on November 30, 1995.

3
<PAGE>

2: Research Series
.............................................................................

> Investment Objective

The series' investment objective is long-term growth of capital and future
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. The series focuses on
companies that MFS believes have favorable prospects for long-term growth,
attractive valuations based on current and expected earnings or cash flow,
dominant or growing market share, and superior management. The series may
invest in companies of any size. The series' investments may include
securities traded on securities exchanges or in the over-the-counter markets.

A committee of investment research analysts selects portfolio securities
for the series. This committee includes investment analysts employed not
only by MFS, but also by MFS International (U.K.) Limited, a wholly owned
subsidiary of MFS. The committee allocates the series' assets among various
industries. Individual analysts then select what they view as the
securities best suited to achieve the series' investment objective within
their assigned industry responsibility.

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

> Principal Risks

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 incurred by 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 purchasing or selling these securities at a fair price.

o Foreign Markets 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:

> 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.

4
<PAGE>

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 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.
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'
shares for each calendar year since they were first offered, assuming the
reinvestment of distributions.

[BAR CHART PLOT POINTS]

1996 22.33%
1997 20.26%
1998 23.39%

[END PLOT POINTS]

During the period shown in the bar chart, the highest quarterly return was
21.65% (for the calendar quarter ended December 31, 1998) and the lowest
quarterly return was (14.66)% (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, 1998
.............................................................................

<TABLE>
<CAPTION>
1 Year Life
<S> <C> <C>
Research Series* +23.39% +22.52%
Standard & Poor's 500 Composite Index**+ +28.58% +28.16%
</TABLE>

---------
* "Life" refers to the period from the commencement of the series'
investment operations, July 26, 1995, through December 31, 1998.
** Source: CDA/Wiesenberger. "Life" refers to the period from August 1,
1995, through December 31, 1998.
+ The Standard & Poor's 500 Composite Index is a broad based, unmanaged
index of common stock total return performance.

> Portfolio Manager

The series is currently managed by a committee comprised of various equity
research analysts employed by the Adviser. The committee has managed the
series since its inception.

5
<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 may invest in foreign equity securities through which it may have
exposure to foreign currencies.

> Principal Risks

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.

> 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

6
<PAGE>

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

Bar Chart

The bar chart shows changes in the annual total returns of the series'
shares for each calendar year since they were first offered, assuming the
reinvestment of distributions.

[BAR CHART PLOT POINTS]

1996 24.46%
1997 29.78%
1998 22.32%

[END PLOT POINTS]

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, 1998
.............................................................................

<TABLE>
<CAPTION>
1 Year Life
<S> <C> <C>
Growth With Income Series* 22.32% 25.98%
Standard & Poor's 500 Composite Index **++ 28.58% 28.16%
</TABLE>

---------
* "Life" refers to the period from the commencement of the series'
investment operations on October 9, 1995, through December 31, 1998.
++ Source: CDA/Wiesenberger. "Life" refers to the period from November
1, 1995, through December 31, 1998.
** The Standard & Poor's 500 Composite Index is a broad based, unmanaged
index of common stock total return performance.

> Portfolio Manager

John D. Laupheimer, a Senior Vice President of the Adviser, has been employed
by the Adviser as a portfolio manager 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 as a portfolio manager since
1986. Mr. Dynan has been the series' portfolio manager since May 1, 1999.

7
<PAGE>

4: Total Return Series
.............................................................................

> Investment Objectives

The series' investment objective is primarily 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.

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 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.

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

8
<PAGE>

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

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.

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.

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:

[dagger] 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.

+ 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.

+ 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.

9
<PAGE>

[dagger} 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.

[dagger] 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

Bar Chart

The bar chart shows changes in the annual total returns of the series'
shares for each calendar year since they were first offered, assuming the
reinvestment of distributions.

[BAR CHART PLOT POINTS]

1996 14.37%
1997 21.30%
1998 12.33%

[END PLOT POINTS]

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 (4.28)% (for the calendar quarter ended September 30,
1998).

10
<PAGE>

Performance Table

Average Annual Total Returns as of December 31, 1998
.............................................................................

<TABLE>
<CAPTION>
1 Year Life
<S> <C> <C>
Total Return Series* +12.33% +18.73%
S&P 500 Composite Index**+ +28.58% +30.41%
Lehman Brothers Government/Corporate Bond Index**++ + 9.49% + 8.58%
Average balanced fund# +13.48% +17.64%
</TABLE>

---------
* "Life" refers to the period from the commencement of the series'
investment operations, January 3, 1995, through December 31, 1998.
** Source: CDA/Wiesenberger. "Life" refers to the period from February 1,
1995, through December 31, 1998.
# Source: Lipper Analytical Services, Inc. "Life" refers to the period
from February 1, 1995, through December 31, 1998.
+ The Standard & Poor's 500 Composite Index is a broad based, unmanaged
index of common stock total return performance.
++ The Lehman Brothers Government/Corporate Bond Index is a broad based,
unmanaged, market-value-weighted index of U.S. Treasury and
government-agency securities (excluding mortgage-backed securities) and
investment-grade domestic corporate debt.

> Portfolio Manager

David M. Calabro, a Senior Vice President of MFS, has been employed by the
Adviser as a portfolio manager 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 by the Adviser as a portfolio manager 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 by the Adviser as a portfolio
manager 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 by
the Adviser as a portfolio manager since 1987. Ms. Nurme is a manager of the
common stock portion of the series' portfolio. Kenneth J. Enright, a Vice
President of MFS, has been employed by the Adviser as a portfolio manager
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.

11
<PAGE>

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

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 policy may not be effective in protecting its value.

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. Frequent trading also
increases transaction costs, which could detract from the series'
performance.

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).

----------------------------
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 $102.9 billion on behalf of approximately 3.8
million investor accounts as of January 31, 1999. As of such date, the MFS
organization managed approximately $73.6 billion of net assets in equity fund
and equity portfolios. Approximately $4.7 billion of the assets managed by
MFS are invested in securities of foreign issuers and foreign denominated
securities of U.S. issuers. 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.

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

The trust offers shares of each of its series 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.

12
<PAGE>

---------------------
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). 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 net
short-term capital gain) to shareholders as dividends at least annually. Any
realized net capital gains are also distributed at least annually.

> Tax Considerations

Each series of the trust is treated as a separate entity for federal income
tax purposes. As long as a series qualifies for treatment as a regulated
investment company (which it has in the past and intends to do so 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
qualified pension and retirement plan sponsors. Consult with the insurance
company which issued your contract or your plan sponsor or financial
advisor to understand the federal tax treatment of your investment.

> Right to Reject 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.

> Market Timing Policies

The series are not designed for professional market timing organizations or
other entities using programmed or frequent exchanges. The series define a
"market timer" as an individual, or organization acting on behalf of one or
more individuals, if the individual or organization makes during the calendar
year six or more exchange requests among the series.

Accounts under common ownership or control, including accounts administered
by market timers, will be aggregated for purposes of this definition.

The series may impose specific limitations on market timers, includng:

o delaying for up to seven days the purchase side of an exchange request by
market timers;

o rejecting or otherwise restricting purchase or exchange requests by market
timers; and

o permitting exchanges by market timers only into certain series.

13
<PAGE>

> 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 similar
investment goals and principal investment policies and risks to 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 5 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.

14
<PAGE>

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

<TABLE>
<CAPTION>
Period Ended
Year Ended December 31, December 31,
1998 1997 1996 1995*
- ---------------------------------------------------------------------------------------------------------------------
<S> <C> <C> <C> <C>
Per share data (for a share outstanding throughout
each period):
Net asset value -- beginning of period ................... $ 16.13 $ 13.24 $ 11.41 $ 10.00
------- ------- ------- --------
Income from investment operations# --
Net investment income (loss)[sec] ....................... $ (0.05) $ (0.06) $ (0.01) $ 0.01
Net realized and unrealized gain on investments and
foreign currency ....................................... 5.55 2.95 1.95 1.74
------- ------- ------- --------
Total from investment operations ...................... $ 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 ......................... $ 21.47 $ 16.13 $ 13.24 $ 11.41
------- ------- ------- --------
Total return ............................................. 34.16% 21.90% 17.02% 17.41%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .............................................. 0.85% 0.90% 1.00% 1.00%+
Net investment income (loss) ............................ (0.29)% (0.38)% (0.08)% 0.10%+
Portfolio turnover ....................................... 71% 112% 96% 73%
Net assets at end of period (000 omitted) ................ $908,987 $384,480 $104,956 $ 3,869
</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.
## The 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. The series' expenses
are calculated without reduction for this expense offset arrangement.
[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:

<TABLE>
<S> <C> <C> <C> <C>
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>

15
<PAGE>

2. Research Series
.............................................................................

---------
* For the period from the commencement of the series' investment
operations, July 26, 1995, through December 31, 1995.
+ Annualized.
++ Not annualized.
# Per share data are based on average shares outstanding.
## The 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. The series' expenses
are calculated without reduction for this expense offset arrangement.
[sec] Prior to January 1, 1998, subject to reimbursement by the series, the
investment adviser agreed to maintain expenses of the series, exclusive
of management fees, at not more than 0.25% of average daily net assets.
To the extent actual expenses were over or under this limitation, the
net investment income (loss) per share and the ratios would have been:

<TABLE>
<S> <C> <C> <C> <C>
Net investment income (loss) .......... -- $ 0.06 $ -- $ (0.08)
Ratios (to average net assets):
Expenses## ........................... -- 0.88% 1.48% 3.90%+
Net investment income (loss) ......... -- 0.38% -- (1.73)%+
</TABLE>

16
<PAGE>

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

<TABLE>
<CAPTION>
Period Ended
Year Ended December 31, December 31,
1998 1997 1996 1995*
<S> <C> <C> <C> <C>
- ----------------------------------------------------------------------------------------------------------------

Per share data (for a share outstanding throughout
each period):
Net asset value -- beginning of period ................... $ 16.44 $ 12.98 $ 10.61 $ 10.00
------- ------- ------- --------
Income from investment operations# --
Net investment income[sec] .............................. $ 0.13 $ 0.16 $ 0.18 $ 0.05
Net realized and unrealized gain on investments and
foreign currency ....................................... 3.54 3.70 2.42 0.61
------- ------- ------- --------
Total from investment operations ...................... $ 3.67 $ 3.86 $ 2.60 $ 0.66
------- ------- ------- --------
Less distributions declared to shareholders --
From net investment income .............................. $ -- $ (0.07) $ (0.09) $ (0.05)
From net realized gain on investments and foreign
currency transactions .................................. -- (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 .......... $ -- $ (0.40) $ (0.23) $ (0.05)
-------- -------- -------- --------
Net asset value -- end of period ......................... $ 20.11 $ 16.44 $ 12.98 $ 10.61
-------- -------- -------- --------
Total return ............................................. 22.32% 29.78% 24.46% 6.64%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .............................................. 0.95% 1.00% 1.01% 1.00%+
Net investment income ................................... 0.73% 0.93% 1.52% 2.20%+
Portfolio turnover ....................................... 57% 42% 41% 2%
Net assets at end of period (000 omitted) ................ $244,310 $ 58,045 $ 9,174 $ 365
</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.
## The 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. The series' expenses are calculated without
reduction for this expense offset arrangement.
[sec] Prior to October 2, 1998, subject to reimbursement by the series, the
investment adviser voluntarily agreed to maintain the expenses of the
series, exclusive of management fees, at not more 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 ratios would
have been:

<TABLE>
<S> <C> <C> <C> <C>
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>

17
<PAGE>

4. Total Return Series
.........................................................................

Per share data (for a share outstanding throughout
each period):
Net asset value -- beginning of period ................... $ 16.63 $ 13.71 $ 12.25 $ 10.00
------- ------- ------- --------
Income from investment operations# --
Net investment income[sec] .............................. $ 0.53 $ 0.52 $ 0.46 $ 0.41
Net realized and unrealized gain on investments and
foreign currency ....................................... 1.49 2.40 1.30 2.32
------- ------- ------- --------
Total from investment operations ...................... $ 2.02 $ 2.92 $ 1.76 $ 2.73
------- ------- ------- --------
Less distributions declared to shareholders --
From net investment income .............................. $ (0.24) $ -- $ (0.21) $ (0.25)
From net realized gain on investments and foreign
currency transactions .................................. (0.29) -- (0.09) (0.23)
-------- ------- -------- --------
Total distributions declared to shareholders .......... $ (0.53) $ -- $ (0.30) $ (0.48)
-------- ------- -------- --------
Net asset value -- end of period ......................... $ 18.12 $ 16.63 $ 13.71 $ 12.25
-------- ------- -------- --------
Total return ............................................. 12.33% 21.30% 14.37% 27.34%++
Ratios (to average net assets)/Supplemental data[sec]:
Expenses## .............................................. 1.00% 1.00% 1.00% 1.00%+
Net investment income ................................... 3.05% 3.25% 3.59% 3.83%+
Portfolio turnover ....................................... 100% 93% 76% 16%
Net assets at end of period (000 omitted) ................ $171,182 $75,612 $ 19,250 $ 2,797
</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.
## The 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. The series' expenses
are calculated without reduction for this expense.
[sec] Subject to reimbursement by the series, the investment adviser
voluntarily agreed to maintain the expenses of the series, exclusive of
management fees, at not more than 0.25% of average daily net assets. To
the extent actual expenses were over/under this limitation, the net
investment income per share and the ratios would have been:

<TABLE>
<S> <C> <C> <C> <C>
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>

18
<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 investment techniques and
practices, which are described, together with their risks, in the SAI.
Investment techniques and practices which are the principal focus of the
series are also described in the Risk Return Summary of the Prospectus.

Symbols [check] permitted -- not permitted
- --------------------------------------------------------------------------------

<TABLE>
<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 [check]
Loans and Other Direct Indebtedness --
Lower Rated Bonds [check]
Municipal Bonds --
Speculative Bonds [check]
U.S. Government Securities [check]
Variable and Floating Rate Obligations [check]
Zero Coupon Bonds, Deferred Interest Bonds
and PIK Bonds [check]
Equity Securities [check]
Foreign Securities Exposure
Brady Bonds --
Depositary Receipts [check]
Dollar-Denominated Foreign Debt Securities --
Emerging Markets [check]
Foreign Securities [check]
Forward Contracts [check]
Futures Contracts [check]
Indexed Securities/Structured Products --
Inverse Floating Rate Obligations --

Investment in Other Investment Companies
Open-End Funds [check]
Closed-End Funds [check]
Lending of Portfolio Securities [check]
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions --*
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies [check]
Options on Futures Contracts [check]
Options on Securities [check]
Options on Stock Indices [check]
Reset Options --
"Yield Curve" Options --
Repurchase Agreements [check]
Restricted Securities [check]
Short Sales --
Short Sales Against the Box --
Short Term Instruments [check]
Swaps and Related Derivative Instruments --
Temporary Borrowings [check]
Temporary Defensive Positions [check]
Warrants [check]
"When-Issued" Securities [check]
</TABLE>

*May be changed only with shareholder approval.

A-1
<PAGE>

------------------- -----------------------------
A p p e n d i x A R e s e a r c h S e r i e s
------------------- -----------------------------

> Investment Techniques and Practices

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

Symbols [check] permitted -- not permitted
- --------------------------------------------------------------------------------

<TABLE>
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclas s
Pass-Through Securities --
Corporate Asset-Backed Securities --
Mortgage Pass-Through Securities --
Stripped Mortgage-Backed Securities --
Corporate Securities [check]
Loans and Other Direct Indebtedness --
Lower Rated Bonds [check]
Municipal Bonds --
Speculative Bonds [check]
U.S. Government Securities [check]
Variable and Floating Rate Obligations [check]
Zero Coupon Bonds, Deferred Interest Bonds and PIK
Bonds --
Equity Securities [check]
Foreign Securities Exposure
Brady Bonds --
Depositary Receipts [check]
Dollar-Denominated Foreign Debt Securities [check]
Emerging Markets [check]
Foreign Securities [check]
Forward Contracts [check]
Futures Contracts --
Indexed Securities/Structured Products [check]
Inverse Floating Rate Obligations --

Investment in Other Investment Companies
Open-End Funds [check]
Closed-End Funds [check]
Lending of Portfolio Securities [check]
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 [check]
Restricted Securities [check]
Short Sales --
Short Sales Against the Box --
Short Term Instruments [check]
Swaps and Related Derivative Instruments --
Temporary Borrowings [check]
Temporary Defensive Positions [check]
Warrants [check]
"When-Issued" Securities --
</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 objectives and investment policies, the Growth
With Income Series may engage in the following investment techniques and
practices, which are described, together with their risks, in the SAI.
Investment techniques and practices which are the principal focus of the
series are also described in the Risk Return Summary of the Prospectus.

Symbols [check] permitted -- not permitted
- --------------------------------------------------------------------------------

<TABLE>
<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 [check]
Loans and Other Direct Indebtedness --
Lower Rated Bonds --
Municipal Bonds --
Speculative Bonds --
U.S. Government Securities --
Variable and Floating Rate Obligations [check]
Zero Coupon Bonds, Deferred Interest Bonds and PIK
Bonds [check]
Equity Securities [check]
Foreign Securities Exposure
Brady Bonds --
Depositary Receipts [check]
Dollar-Denominated Foreign Debt Securities --
Emerging Markets [check]
Foreign Securities [check]
Forward Contracts [check]
Futures Contracts [check]
Indexed Securities/Structured Products --
Inverse Floating Rate Obligations --

Investment in Other Investment Companies
Open-End [check]
Closed-End [check]
Lending of Portfolio Securities [check]
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions --*
Reverse Repurchase Agreements --*
Options
Options on Foreign Currencies [check]
Options on Futures Contracts [check]
Options on Securities [check]
Options on Stock Indices [check]
Reset Options --
"Yield Curve" Options --
Repurchase Agreements [check]
Restricted Securities [check]
Short Sales --
Short Sales Against the Box [check]
Short Term Instruments [check]
Swaps and Related Derivative Instruments --
Temporary Borrowings [check]
Temporary Defensive Positions [check]
Warrants [check]
"When-Issued" Securities [check]
</TABLE>

*May be changed only with shareholder approval.

A-3
<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 objectives and investment policies, the Total
Return Series may engage in the following investment techniques and
practices, which are described, together with their risks, in the SAI.
Investment techniques and practices which are the principal focus of the
series are also described in the Risk Return Summary of the Prospectus.

Symbols [check] permitted -- not permitted
- --------------------------------------------------------------------------------

<TABLE>
<S> <C>
Debt Securities
Asset-Backed Securities
Collateralized Mortgage Obligations and Multiclass
Pass-Through Securities [check]
Corporate Asset-Backed Securities [check]
Mortgage Pass-Through Securities [check]
Stripped Mortgage-Backed Securities [check]
Corporate Securities [check]
Loans and Other Direct Indebtedness [check]
Lower Rated Bonds [check]
Municipal Bonds [check]
Speculative Bonds [check]
U.S. Government Securities [check]
Variable and Floating Rate Obligations [check]
Zero Coupon Bonds, Deferred Interest Bonds and PIK
Bonds [check]
Equity Securities [check]
Foreign Securities Exposure
Brady Bonds [check]
Depositary Receipts [check]
Dollar-Denominated Foreign Debt Securities [check]
Emerging Markets [check]
Foreign Securities [check]
Forward Contracts [check]
Futures Contracts [check]
Indexed Securities/Structured Products [check]
Inverse Floating Rate Obligations [check]

Investment in Other Investment Companies
Open-End Funds [check]
Closed-End Funds [check]
Lending of Portfolio Securities [check]
Leveraging Transactions
Bank Borrowings --*
Mortgage "Dollar-Roll" Transactions *
Reverse Repurchase Agreements *
Options
Options on Foreign Currencies [check]
Options on Futures Contracts [check]
Options on Securities [check]
Options on Stock Indices [check]
Reset Options [check]
"Yield Curve" Options [check]
Repurchase Agreements [check]
Restricted Securities [check]
Short Sales --
Short Sales Against the Box --
Short Term Instruments [check]
Swaps and Related Derivative Instruments [check]
Temporary Borrowings [check]
Temporary Defensive Positions [check]
Warrants [check]
"When-Issued" Securities [check]
</TABLE>

*May be changed only with shareholder approval.

A-4
<PAGE>

MFS(R) 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, 1999, 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., 20549-6009

Information on the operation of the Public Reference Room may be obtained by
calling the Commission at 1-800-SEC-0330. Reports and other information about
the trust and its series are available 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 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