<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000867969
<NAME> MFS INSTITUTIONAL TRUST
<SERIES>
<NUMBER> 06
<NAME> MFS INSTITUTIONAL MID CAP GROWTH FUND
<MULTIPLIER> 1
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> JUN-30-2000
<PERIOD-START> JUL-01-1999
<PERIOD-END> JUN-30-2000
<INVESTMENTS-AT-COST> 106819491
<INVESTMENTS-AT-VALUE> 126813057
<RECEIVABLES> 944117
<ASSETS-OTHER> 440
<OTHER-ITEMS-ASSETS> 29870654
<TOTAL-ASSETS> 157628268
<PAYABLE-FOR-SECURITIES> 733584
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 29890376
<TOTAL-LIABILITIES> 30623960
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 68832820
<SHARES-COMMON-STOCK> 4869831
<SHARES-COMMON-PRIOR> 3802791
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 38177922
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 19993566
<NET-ASSETS> 127004308
<DIVIDEND-INCOME> 113636
<INTEREST-INCOME> 192684
<OTHER-INCOME> 0
<EXPENSES-NET> (642734)
<NET-INVESTMENT-INCOME> (336414)
<REALIZED-GAINS-CURRENT> 43457479
<APPREC-INCREASE-CURRENT> 12767114
<NET-CHANGE-FROM-OPS> 55888179
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> (11347449)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 918026
<NUMBER-OF-SHARES-REDEEMED> (366853)
<SHARES-REINVESTED> 515867
<NET-CHANGE-IN-ASSETS> 65101982
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 6404306
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 538196
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 673744
<AVERAGE-NET-ASSETS> 89697348
<PER-SHARE-NAV-BEGIN> 16.28
<PER-SHARE-NII> (0.08)
<PER-SHARE-GAIN-APPREC> 12.51
<PER-SHARE-DIVIDEND> 0
<PER-SHARE-DISTRIBUTIONS> (2.63)
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 26.08
<EXPENSE-RATIO> 0.72
</TABLE>
