<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000783740
<NAME> MFS SERIES TRUST X
<SERIES>
<NUMBER> 042
<NAME> MFS STRATEGIC VALUE FUND CLASS I
<MULTIPLIER> 1
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> JUL-31-2000
<PERIOD-START> AUG-01-1999
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<PAID-IN-CAPITAL-COMMON> 1071007
<SHARES-COMMON-STOCK> 87187
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<ACCUMULATED-NII-CURRENT> 3889
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<OTHER-INCOME> (194)
<EXPENSES-NET> (16756)
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<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (7509)
<DISTRIBUTIONS-OF-GAINS> (254824)
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<NUMBER-OF-SHARES-SOLD> 115948
<NUMBER-OF-SHARES-REDEEMED> (139340)
<SHARES-REINVESTED> 24402
<NET-CHANGE-IN-ASSETS> (867551)
<ACCUMULATED-NII-PRIOR> 4646
<ACCUMULATED-GAINS-PRIOR> 208165
<OVERDISTRIB-NII-PRIOR> 0
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<GROSS-ADVISORY-FEES> 10054
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<AVERAGE-NET-ASSETS> 1337341
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<PER-SHARE-DIVIDEND> (0.09)
<PER-SHARE-DISTRIBUTIONS> (2.95)
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 12.19
<EXPENSE-RATIO> 1.26
</TABLE>
