MFS Bond Fund (Prospectus Summary) | MFS Bond Fund

Summary of Key Information

Investment Objective

The fund's investment objective is to seek total return with an emphasis on
current income, but also considering capital appreciation.

Fees and Expenses

This table describes the fees and expenses that you may pay when you buy and
hold shares of the fund.

You may qualify for sales charge reductions if you and certain members of your
family invest, or agree to invest in the future, at least $50,000 in MFS Funds.
More information about these and other waivers and reductions is available from
your financial intermediary and in "Sales Charges and Waivers or Reductions" on
page 8 of the fund's prospectus and "Waivers of Sales Charges" on page 12 of the
fund's statement of additional information Part I.

Shareholder Fees (fees paid directly from your investment):

Shareholder Fees MFS Bond Fund	A		B	C	I	W	R1	R2	R3	R4
Shareholder Fees, Column Name	A		B	C	I AND W	I AND W	ALL R	ALL R	ALL R	ALL R
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	4.75%		none	none	none	none	none	none	none	none
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)	1.00%	[1]	4.00%	1.00%	none	none	none	none	none	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):

Annual Fund Operating Expenses MFS Bond Fund	A	B	C	I	W	R1	R2	R3	R4
Operating Expenses, Column Name	A	B	C	I	W	R1	R2	R3	R4
Management Fee	0.39%	0.39%	0.39%	0.39%	0.39%	0.39%	0.39%	0.39%	0.39%
Distribution and/or Service (12b-1) Fees	0.25%	1.00%	1.00%	none	0.10%	1.00%	0.50%	0.25%	none
Other Expenses	0.21%	0.21%	0.21%	0.21%	0.21%	0.21%	0.21%	0.21%	0.21%
Total Annual Fund Operating Expenses	0.85%	1.60%	1.60%	0.60%	0.70%	1.60%	1.10%	0.85%	0.60%

Example

This example is intended to help you compare the cost of investing in the fund
with the cost of investing in other mutual funds.

The example assumes that: you invest $10,000 in the fund for the time periods
indicated and you redeem your shares at the end of the time periods (unless
otherwise indicated); your investment has a 5% return each year; and the fund's
operating expenses remain the same.

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

Expense Example MFS Bond Fund (USD $)	Expense Example, By Year, Column Name	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years	Expense Example, With Redemption, 5 Years	Expense Example, With Redemption, 10 Years
A	Class A Shares	558	733	924	1,474
B	Class B Shares assuming redemption at end of period	563	805	1,071	1,699
C	Class C Shares assuming redemption at end of period	263	505	871	1,900
I	Class I Shares	61	192	335	750
W	Class W Shares	72	224	390	871
R1	Class R1 Shares	163	505	871	1,900
R2	Class R2 Shares	112	350	606	1,340
R3	Class R3 Shares	87	271	471	1,049
R4	Class R4 Shares	61	192	335	750

Expense Example, No Redemption MFS Bond Fund (USD $)	Expense Example, No Redemption, By Year, Column Name	Expense Example, No Redemption, 1 Year	Expense Example, No Redemption, 3 Years	Expense Example, No Redemption, 5 Years	Expense Example, No Redemption, 10 Years
B	Class B Shares assuming no redemption at end of period	163	505	871	1,699
C	Class C Shares assuming no redemption at end of period	163	505	871	1,900

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells
securities (or "turns over" its portfolio). A higher portfolio turnover rate may
indicate higher transaction costs and may result in higher taxes when shares are
held in a taxable account. These transaction costs, which are not reflected in
"Annual Fund Operating Expenses" or in the "Example," affect the fund's
performance.  During the most recent fiscal year, the fund's portfolio turnover
rate was 58% of the average value of its portfolio.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund's investment adviser)
normally invests at least 80% of the fund's net assets in debt instruments.

MFS invests the majority of the fund's assets in corporate debt instruments, but
may also invest in other types of debt instruments. MFS primarily invests the
fund's assets in investment grade debt instruments, but may also invest in lower
quality debt instruments.

MFS may invest the fund's assets in foreign securities, including emerging
market securities.

While MFS may use derivatives for any investment purpose, to the extent MFS uses
derivatives, MFS expects to use derivatives primarily to increase or decrease
exposure to a particular market, segment of the market, or security, to increase
or decrease interest rate or currency exposure, or as alternatives to direct
investments. Derivatives include futures, forward contracts, options, structured
securities, inverse floating rate instruments, and swaps.

MFS uses a bottom-up investment approach to buying and selling investments for
the fund. Investments are selected primarily based on fundamental analysis of
individual instruments and their issuers in light of issuers' current financial
condition and current market, economic, political, and regulatory conditions.
Factors considered may include the instrument's credit quality, collateral
characteristics, and indenture provisions, and the issuer's management ability,
capital structure, leverage, and ability to meet its current obligations.
Quantitative models that systematically evaluate the structure of the debt
instrument and its features may also be considered.

Principal Risks

As with any mutual fund, the fund may not achieve its objective and/or you could
lose money on your investment in the fund. An investment in the fund is not a
bank deposit and is not insured or guaranteed by the Federal Deposit Insurance
Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Interest Rate Risk:  The price of a debt instrument falls when interest rates
rise and rises when interest rates fall. Instruments with longer maturities, or
that do not pay current interest, are more sensitive to interest rate changes.

Credit Risk:  The price of a debt instrument depends, in part, on the credit
quality of the issuer, borrower, counterparty, or underlying collateral and can
decline in response to changes in the financial condition of the issuer,
borrower, counterparty, or underlying collateral, or changes in specific or
general market, economic, industry, political, regulatory, geopolitical, or
other conditions.

Lower quality debt instruments (commonly referred to as "high yield securities"
or "junk bonds") can involve a substantially greater risk of default or can
already be in default, and their values can decline significantly. Lower quality
debt instruments are regarded as having predominantly speculative
characteristics. Lower quality debt instruments tend to be more sensitive to
adverse news about the issuer, or the market or economy in general, than higher
quality debt instruments.

Foreign and Emerging Markets Risk:  Exposure to foreign markets, especially
emerging markets, through issuers or currencies can involve additional risks
relating to market, economic, political, regulatory, geopolitical, or other
conditions. These factors can make foreign investments, especially those in
emerging markets, more volatile and less liquid than U.S. investments. In
addition, foreign markets can react differently to these conditions than the
U.S. market. Emerging markets can have less developed markets and less developed
legal, regulatory, and accounting systems, and greater political, social, and
economic instability than developed markets.

Currency Risk:  The value of foreign currencies relative to the U.S. dollar
fluctuates in response to market, economic, political, regulatory, geopolitical
or other conditions, and a decline in the value of a foreign currency versus the
U.S. dollar reduces the value in U.S. dollars of investments denominated in that
foreign currency.

Prepayment/Extension Risk:  Instruments subject to prepayment and/or extension
can reduce the potential for gain for the instrument's holders if the instrument
is prepaid and increase the potential for loss if the maturity of the instrument
is extended.

Inflation-Adjusting Risk:  Interest payments on inflation-adjusted debt
instruments can be unpredictable and vary based on the level of inflation. If
inflation is negative, principal and income can both decline.

Municipal Risk:  The price of a municipal instrument can be volatile and
significantly affected by adverse tax or court rulings, legislative or political
changes, changes in specific or general market and economic conditions, and the
financial condition of municipal issuers and insurers. Because many municipal
instruments are issued to finance similar projects, conditions in these
industries can significantly affect the fund and the overall municipal market.

Derivatives Risk:  Derivatives can be highly volatile and involve risks in
addition to the risks of the underlying indicator(s) on which the derivative is
based. Gains or losses from derivatives can be substantially greater than the
derivatives' original cost.  Derivatives can involve leverage.

Leveraging Risk:  Leverage involves investment exposure in an amount exceeding
the initial investment. Leverage can cause increased volatility by magnifying
gains or losses.

Liquidity Risk:  It may not be possible to sell certain investments, types of
investments, and/or segments of the market at any particular time or at an
acceptable price.

Counterparty and Third Party Risk:  Transactions involving a counterparty or
third party other than the issuer of the instrument are subject to the credit
risk of the counterparty or third party, and to the counterparty's or third
party's ability to perform in accordance with the terms of the transaction.

Investment Selection Risk:  The MFS analysis of an investment can be incorrect
and can lead to an investment focus that results in the fund underperforming
other funds with similar investment strategies and/or underperforming the
markets in which the fund invests.

Performance Information

The bar chart and performance table below are intended to provide some
indication of the risks of investing in the fund by showing changes in the
fund's performance over time and how the fund's performance over time compares
with that of a broad measure of market performance and one or more other
measures of performance for markets in which the fund may invest.

The fund's past performance (before and after taxes) does not necessarily
indicate how the fund will perform in the future. Updated performance is
available online at mfs.com or by calling 1-800-225-2606.

The bar chart does not take into account any sales charges (loads) that you
may be required to pay upon purchase or redemption of the fund's shares.
If these sales charges were included, they would reduce the returns shown.

Class A Bar Chart.

The total return for the six-month period ended June 30, 2011 was 3.85%. During
the period(s) shown in the bar chart, the highest quarterly return was 11.30%
(for the calendar quarter ended June 30, 2009) and the lowest quarterly return
was (5.18)% (for the calendar quarter ended September 30, 2008).

Performance Table.

Average Annual Total Returns (for the Periods Ended December 31, 2010)

Average Annual Total Returns MFS Bond Fund	Average Annual Returns, Label	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
A	A Shares Returns Before Taxes	5.94%	5.86%	6.28%
B	B Shares Returns Before Taxes	6.42%	5.82%	6.21%
C	C Shares Returns Before Taxes	9.42%	6.16%	6.06%
I	I Shares Returns Before Taxes	11.50%	7.18%	7.11%
W	W Shares Returns Before Taxes
R1	R1 Shares Returns Before Taxes	10.42%	6.10%	5.90%
R2	R2 Shares Returns Before Taxes	10.87%	6.59%	6.42%
R3	R3 Shares Returns Before Taxes	11.22%	6.87%	6.69%
R4	R4 Shares Returns Before Taxes	11.50%	7.16%	6.99%
After Taxes on Distributions A	A Shares Returns After Taxes on Distributions	3.89%	3.81%	4.11%
After Taxes on Distributions and Sales A	A Shares Returns After Taxes on Distributions and Sale of Fund Shares	3.81%	3.75%	4.04%
Barclays Capital U.S. Credit Bond Index	Index Comparison (Reflects no deduction for fees, expenses or taxes) Barclays Capital U.S. Credit Bond Index	8.47%	5.98%	6.55%

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of state and local
taxes. Your actual after-tax returns will depend on your own tax situation, and
may differ from those shown. The after-tax returns shown are not relevant to
investors who hold their shares through tax-deferred arrangements, such as
401(k) plans or individual retirement accounts. The after-tax returns are shown
for only one of the fund's classes of shares, and after-tax returns for the
fund's other classes of shares will vary from the returns shown.

[1] On shares purchased without an initial sales charge and redeemed within 24 months of purchase.