<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information
extracted from The MassMutual Institutional Funds, Inc.
form N-SAR for the period ended June 30, 2000
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 011
<NAME> Prime Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-END> JUN-30-2000
<INVESTMENTS-AT-COST> 445,566,790
<INVESTMENTS-AT-VALUE> 445,603,325
<RECEIVABLES> 917
<ASSETS-OTHER> 1,636
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 445,605,878
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 186,845
<TOTAL-LIABILITIES> 186,845
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 433,534,040
<SHARES-COMMON-STOCK> 83,504
<SHARES-COMMON-PRIOR> 23,431
<ACCUMULATED-NII-CURRENT> 12,000,098
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> (78,570)
<ACCUM-APPREC-OR-DEPREC> (36,535)
<NET-ASSETS> 445,419,033
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 12,890,104
<OTHER-INCOME> 0
<EXPENSES-NET> 946,330
<NET-INVESTMENT-INCOME> 11,943,774
<REALIZED-GAINS-CURRENT> (36,594)
<APPREC-INCREASE-CURRENT> (13,660)
<NET-CHANGE-FROM-OPS> 11,893,520
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 902,525
<NUMBER-OF-SHARES-REDEEMED> 842,452
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 81,831,646
<ACCUMULATED-NII-PRIOR> 56,324
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> (41,976)
<GROSS-ADVISORY-FEES> 707,810
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 946,330
<AVERAGE-NET-ASSETS> 406,685,416
<PER-SHARE-NAV-BEGIN> 151.41
<PER-SHARE-NII> 4.27
<PER-SHARE-GAIN-APPREC> (0.17)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 155.51
<EXPENSE-RATIO> 0.95
</TABLE>
