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<PAGE> PAGE 2
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<PAGE> PAGE 3
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<PAGE> PAGE 4
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<PAGE> PAGE 5
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<PAGE> PAGE 10
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<PAGE> PAGE 11
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<PAGE> PAGE 12
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<PAGE> PAGE 14
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<PAGE> PAGE 16
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<PAGE> PAGE 18
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<PAGE> PAGE 20
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<PAGE> PAGE 21
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<PAGE> PAGE 22
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008 A000501 MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
008 B000501 A
008 C000501 801-8059
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<PAGE> PAGE 23
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<PAGE> PAGE 24
062 D000500 0.0
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069 000500 N
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070 A020500 N
070 B010500 Y
070 B020500 N
070 C010500 Y
070 C020500 N
070 D010500 Y
070 D020500 N
070 E010500 Y
070 E020500 N
070 F010500 Y
070 F020500 N
070 G010500 Y
070 G020500 N
070 H010500 Y
070 H020500 N
070 I010500 N
070 I020500 N
070 J010500 Y
070 J020500 N
070 K010500 Y
070 K020500 N
070 L010500 Y
070 L020500 Y
070 M010500 Y
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<PAGE> PAGE 25
070 P010500 Y
070 P020500 N
070 Q010500 N
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<PAGE> PAGE 26
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008 A000601 MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
008 B000601 A
008 C000601 801-8059
008 D010601 SPRINGFIELD
008 D020601 MA
008 D030601 01111
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008 A000602 DAVID L. BABSON AND COMPANY INCORPORATED
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015 A000601 INVESTORS BANK & TRUST COMPANY
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<PAGE> PAGE 27
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<PAGE> PAGE 28
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<PAGE> PAGE 29
070 K010600 Y
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<PAGE> PAGE 30
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008 A000701 MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
008 B000701 A
008 C000701 801-8059
008 D010701 SPRINGFIELD
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008 D030701 01111
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008 A000702 HARBOURVIEW ASSET MANAGEMENT CORPORATION
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<PAGE> PAGE 31
008 D030702 10048
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015 A000701 INVESTORS BANK & TRUST COMPANY
015 B000701 C
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015 A000702 CITIBANK
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015 A000703 CHASE MANHATTAN BANK
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015 A000704 NATIONAL AUSTRALIAN BANK
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015 A000705 EUROCLEAR
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015 A000706 STANDARD CHARTERED BANK
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015 D020706 EC2V 7SB
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015 A000707 BANKBOSTON
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015 C030707 02110
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015 A000708 BANK OF IRELAND
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<PAGE> PAGE 32
015 C010709 MEXICO CITY
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015 A000710 BARCLAYS BANK
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015 C010710 LONDON
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015 D020710 EC3N 4HJ
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015 A000711 THE STANDARD BANK OF SOUTH AFRICA LTD
015 B000711 S
015 C010711 JOHANNESBURG
015 D010711 SOUTH AFRICA
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015 A000712 ROYAL TRUST CORPORATION OF CANADA
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025 A000701 CREDIT SUISSE GROUP
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<PAGE> PAGE 33
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<PAGE> PAGE 34
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<PAGE> PAGE 35
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<PAGE> PAGE 36
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SIGNATURE STEPHEN KUHN
TITLE VICE PRESIDENT
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 31
<NAME> Core Bond Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
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<ACCUMULATED-NET-GAINS> 4,681,795
<OVERDISTRIBUTION-GAINS> 0
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<NET-ASSETS> 136,157
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 4,361
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<EXPENSES-NET> 794
<NET-INVESTMENT-INCOME> 3,567
<REALIZED-GAINS-CURRENT> 1,294
<APPREC-INCREASE-CURRENT> 125
<NET-CHANGE-FROM-OPS> 4,986
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
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<NUMBER-OF-SHARES-SOLD> 13,112
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<NET-CHANGE-IN-ASSETS> 4,986
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<GROSS-ADVISORY-FEES> 1,083,805
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,312,380
<AVERAGE-NET-ASSETS> 133,482
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.27
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<RETURNS-OF-CAPITAL> 0.00
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<EXPENSE-RATIO> 1.20
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</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 32
<NAME> Core Bond Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 491,703,700
<INVESTMENTS-AT-VALUE> 508,650,204
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<TOTAL-LIABILITIES> 4,206,521
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 473,759,756
<SHARES-COMMON-STOCK> 26,824
<SHARES-COMMON-PRIOR> 24,644
<ACCUMULATED-NII-CURRENT> 15,655,732
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 4,681,795
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 16,880,353
<NET-ASSETS> 279,141
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 8,931
<OTHER-INCOME> 0
<EXPENSES-NET> 1,016
<NET-INVESTMENT-INCOME> 7,915
<REALIZED-GAINS-CURRENT> 2,649
<APPREC-INCREASE-CURRENT> 259
<NET-CHANGE-FROM-OPS> 10,823
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 26,824
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 10,822
<ACCUMULATED-NII-PRIOR> 1,094,301
<ACCUMULATED-GAINS-PRIOR> 69,810
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,083,805
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,312,380
<AVERAGE-NET-ASSETS> 273,353
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.30
<PER-SHARE-GAIN-APPREC> 0.11
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.41
<EXPENSE-RATIO> 0.75
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 33
<NAME> Core Bond Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 491,703,700
<INVESTMENTS-AT-VALUE> 508,650,204
<RECEIVABLES> 6,529,347
<ASSETS-OTHER> 4,606
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 515,184,157
<PAYABLE-FOR-SECURITIES> 3,410,559
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 795,962
<TOTAL-LIABILITIES> 4,206,521
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 473,759,756
<SHARES-COMMON-STOCK> 45,359,748
<SHARES-COMMON-PRIOR> 42,182,957
<ACCUMULATED-NII-CURRENT> 15,655,732
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 4,681,795
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 16,880,353
<NET-ASSETS> 510,562,338
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 15,860,519
<OTHER-INCOME> 0
<EXPENSES-NET> 1,310,570
<NET-INVESTMENT-INCOME> 14,549,949
<REALIZED-GAINS-CURRENT> 4,608,042
<APPREC-INCREASE-CURRENT> 420,663
<NET-CHANGE-FROM-OPS> 19,578,654
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 9,805,388
<NUMBER-OF-SHARES-REDEEMED> 6,628,597
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 54,631,669
<ACCUMULATED-NII-PRIOR> 1,094,301
<ACCUMULATED-GAINS-PRIOR> 69,810
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,083,805
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,312,380
<AVERAGE-NET-ASSETS> 485,276,010
<PER-SHARE-NAV-BEGIN> 10.81
<PER-SHARE-NII> 0.32
<PER-SHARE-GAIN-APPREC> 0.13
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 11.26
<EXPENSE-RATIO> 0.54
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 51
<NAME> Value Equity Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> JUN-30-1998
<INVESTMENTS-AT-COST> 2,223,742,407
<INVESTMENTS-AT-VALUE> 3,442,210,914
<RECEIVABLES> 9,275,272
<ASSETS-OTHER> 162
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 3,451,486,348
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3,344,554
<TOTAL-LIABILITIES> 3,344,554
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,994,245,323
<SHARES-COMMON-STOCK> 19,598
<SHARES-COMMON-PRIOR> 11,555
<ACCUMULATED-NII-CURRENT> 29,903,954
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 205,524,010
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,218,468,507
<NET-ASSETS> 212,738
<DIVIDEND-INCOME> 2,142
<INTEREST-INCOME> 195
<OTHER-INCOME> 0
<EXPENSES-NET> 1,245
<NET-INVESTMENT-INCOME> 1,092
<REALIZED-GAINS-CURRENT> 9,569
<APPREC-INCREASE-CURRENT> 6,082
<NET-CHANGE-FROM-OPS> 16,743
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 19,598
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 16,726
<ACCUMULATED-NII-PRIOR> 1,297,337
<ACCUMULATED-GAINS-PRIOR> 49,859,885
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 7,600,422
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 9,097,765
<AVERAGE-NET-ASSETS> 209,451
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.05
<PER-SHARE-GAIN-APPREC> 0.81
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.86
<EXPENSE-RATIO> 1.20
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 52
<NAME> Value Equity Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> JUN-30-1998
<INVESTMENTS-AT-COST> 2,223,742,407
<INVESTMENTS-AT-VALUE> 3,442,210,914
<RECEIVABLES> 9,275,272
<ASSETS-OTHER> 162
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 3,451,486,348
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3,344,554
<TOTAL-LIABILITIES> 3,344,554
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,994,245,323
<SHARES-COMMON-STOCK> 40,074
<SHARES-COMMON-PRIOR> 23,532
<ACCUMULATED-NII-CURRENT> 29,903,954
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 205,524,010
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,218,468,507
<NET-ASSETS> 435,928
<DIVIDEND-INCOME> 4,319
<INTEREST-INCOME> 394
<OTHER-INCOME> 0
<EXPENSES-NET> 1,591
<NET-INVESTMENT-INCOME> 3,122
<REALIZED-GAINS-CURRENT> 19,583
<APPREC-INCREASE-CURRENT> 12,428
<NET-CHANGE-FROM-OPS> 35,133
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 40,074
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 35,167
<ACCUMULATED-NII-PRIOR> 1,297,337
<ACCUMULATED-GAINS-PRIOR> 49,859,885
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 7,600,422
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 9,097,765
<AVERAGE-NET-ASSETS> 428,723
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.08
<PER-SHARE-GAIN-APPREC> 0.80
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.88
<EXPENSE-RATIO> 0.75
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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 30,1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 53
<NAME> Value Equity Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> JUN-30-1998
<INVESTMENTS-AT-COST> 2,223,742,407
<INVESTMENTS-AT-VALUE> 3,442,210,914
<RECEIVABLES> 9,275,272
<ASSETS-OTHER> 162
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 3,451,486,348
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3,344,554
<TOTAL-LIABILITIES> 3,344,554
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,994,245,323
<SHARES-COMMON-STOCK> 186,220,707
<SHARES-COMMON-PRIOR> 188,089,578
<ACCUMULATED-NII-CURRENT> 29,903,954
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 205,524,010
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,218,468,507
<NET-ASSETS> 3,447,493,128
<DIVIDEND-INCOME> 34,545,041
<INTEREST-INCOME> 3,152,291
<OTHER-INCOME> 0
<EXPENSES-NET> 9,094,929
<NET-INVESTMENT-INCOME> 28,602,403
<REALIZED-GAINS-CURRENT> 155,634,973
<APPREC-INCREASE-CURRENT> 99,032,345
<NET-CHANGE-FROM-OPS> 283,269,721
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 21,107,830
<NUMBER-OF-SHARES-REDEEMED> 22,976,701
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 249,645,263
<ACCUMULATED-NII-PRIOR> 1,297,337
<ACCUMULATED-GAINS-PRIOR> 49,859,885
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 7,600,422
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 9,097,765
<AVERAGE-NET-ASSETS> 3,405,321,337
<PER-SHARE-NAV-BEGIN> 17.00
<PER-SHARE-NII> 0.15
<PER-SHARE-GAIN-APPREC> 1.36
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 18.51
<EXPENSE-RATIO> 0.54
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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 30,1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 11
<NAME> Prime Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 250,503,307
<INVESTMENTS-AT-VALUE> 250,485,260
<RECEIVABLES> 744,833
<ASSETS-OTHER> 2,671
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 251,232,764
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3,122,280
<TOTAL-LIABILITIES> 3,122,280
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 241,554,696
<SHARES-COMMON-STOCK> 11,432
<SHARES-COMMON-PRIOR> 758
<ACCUMULATED-NII-CURRENT> 6,593,769
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (19,934)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (18,047)
<NET-ASSETS> 116,950
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 3,323
<OTHER-INCOME> 0
<EXPENSES-NET> 689
<NET-INVESTMENT-INCOME> 2,634
<REALIZED-GAINS-CURRENT> (1)
<APPREC-INCREASE-CURRENT> 2
<NET-CHANGE-FROM-OPS> 2,635
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 11,432
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 2,635
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (18,160)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 564,949
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 687,794
<AVERAGE-NET-ASSETS> 115,623
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.23
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.23
<EXPENSE-RATIO> 1.20
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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 30,1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 12
<NAME> Prime Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 250,503,307
<INVESTMENTS-AT-VALUE> 250,485,260
<RECEIVABLES> 744,833
<ASSETS-OTHER> 2,671
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 251,232,764
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3,122,280
<TOTAL-LIABILITIES> 3,122,280
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 241,554,696
<SHARES-COMMON-STOCK> 23,374
<SHARES-COMMON-PRIOR> 1,547
<ACCUMULATED-NII-CURRENT> 6,593,769
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (19,934)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (18,047)
<NET-ASSETS> 239,661
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 6,802
<OTHER-INCOME> 0
<EXPENSES-NET> 882
<NET-INVESTMENT-INCOME> 5,920
<REALIZED-GAINS-CURRENT> (2)
<APPREC-INCREASE-CURRENT> 4
<NET-CHANGE-FROM-OPS> 5,922
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 23,374
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 5,922
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (18,160)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 564,949
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 687,794
<AVERAGE-NET-ASSETS> 236,675
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.25
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.25
<EXPENSE-RATIO> 0.75
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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 30,1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 13
<NAME> Prime Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> Dec-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 250,503,307
<INVESTMENTS-AT-VALUE> 250,485,260
<RECEIVABLES> 744,833
<ASSETS-OTHER> 2,671
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 251,232,764
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3,122,280
<TOTAL-LIABILITIES> 3,122,280
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 241,554,696
<SHARES-COMMON-STOCK> 1,600,293
<SHARES-COMMON-PRIOR> 1,600,181
<ACCUMULATED-NII-CURRENT> 6,593,769
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (19,934)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (18,047)
<NET-ASSETS> 247,753,873
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 7,271,438
<OTHER-INCOME> 0
<EXPENSES-NET> 686,223
<NET-INVESTMENT-INCOME> 6,585,215
<REALIZED-GAINS-CURRENT> (1,771)
<APPREC-INCREASE-CURRENT> 3,105
<NET-CHANGE-FROM-OPS> 6,586,549
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 1,558,055
<NUMBER-OF-SHARES-REDEEMED> 1,557,944
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 6,383,460
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (18,160)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 564,949
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 687,794
<AVERAGE-NET-ASSETS> 252,817,063
<PER-SHARE-NAV-BEGIN> 150.84
<PER-SHARE-NII> 3.98
<PER-SHARE-GAIN-APPREC> 0.00
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 154.82
<EXPENSE-RATIO> 0.55
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 61
<NAME> Small CAP Value Equity Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 523,063,066
<INVESTMENTS-AT-VALUE> 724,951,459
<RECEIVABLES> 7,697,307
<ASSETS-OTHER> 2,117
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 732,650,883
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 852,428
<TOTAL-LIABILITIES> 852,428
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 487,034,129
<SHARES-COMMON-STOCK> 19,244
<SHARES-COMMON-PRIOR> 11,677
<ACCUMULATED-NII-CURRENT> 2,534,873
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 40,341,060
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 201,888,393
<NET-ASSETS> 196,261
<DIVIDEND-INCOME> 1,074
<INTEREST-INCOME> 254
<OTHER-INCOME> 0
<EXPENSES-NET> 1,279
<NET-INVESTMENT-INCOME> 49
<REALIZED-GAINS-CURRENT> 10,551
<APPREC-INCREASE-CURRENT> (6,810)
<NET-CHANGE-FROM-OPS> 3,790
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 19,244
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 3,790
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 2,217,759
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,973,243
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,307,335
<AVERAGE-NET-ASSETS> 198,407
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.00
<PER-SHARE-GAIN-APPREC> 0.20
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.20
<EXPENSE-RATIO> 1.30
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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 30,1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 62
<NAME> Small CAP Value Equity Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 523,063,066
<INVESTMENTS-AT-VALUE> 724,951,459
<RECEIVABLES> 7,697,307
<ASSETS-OTHER> 2,117
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 732,650,883
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 852,428
<TOTAL-LIABILITIES> 852,428
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 487,034,129
<SHARES-COMMON-STOCK> 39,393
<SHARES-COMMON-PRIOR> 23,731
<ACCUMULATED-NII-CURRENT> 2,534,873
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 40,341,060
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 201,888,393
<NET-ASSETS> 402,532
<DIVIDEND-INCOME> 2,200
<INTEREST-INCOME> 519
<OTHER-INCOME> 0
<EXPENSES-NET> 1,712
<NET-INVESTMENT-INCOME> 1,007
<REALIZED-GAINS-CURRENT> 21,608
<APPREC-INCREASE-CURRENT> (13,969)
<NET-CHANGE-FROM-OPS> 8,646
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 39,393
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 8,646
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 2,217,759
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,973,243
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,307,335
<AVERAGE-NET-ASSETS> 406,493
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.03
<PER-SHARE-GAIN-APPREC> 0.19
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.22
<EXPENSE-RATIO> 0.85
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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 30,1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 63
<NAME> Small CAP Value Equity Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 523,063,066
<INVESTMENTS-AT-VALUE> 724,951,459
<RECEIVABLES> 7,697,307
<ASSETS-OTHER> 2,117
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 732,650,883
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 852,428
<TOTAL-LIABILITIES> 852,428
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 487,034,129
<SHARES-COMMON-STOCK> 43,033,037
<SHARES-COMMON-PRIOR> 41,565,529
<ACCUMULATED-NII-CURRENT> 2,534,873
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 40,341,060
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 201,888,393
<NET-ASSETS> 731,199,662
<DIVIDEND-INCOME> 3,913,930
<INTEREST-INCOME> 924,231
<OTHER-INCOME> 0
<EXPENSES-NET> 2,304,344
<NET-INVESTMENT-INCOME> 2,533,817
<REALIZED-GAINS-CURRENT> 38,091,142
<APPREC-INCREASE-CURRENT> (25,904,564)
<NET-CHANGE-FROM-OPS> 14,720,395
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 8,122,329
<NUMBER-OF-SHARES-REDEEMED> 6,654,821
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 40,821,362
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 2,217,759
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,973,243
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,307,335
<AVERAGE-NET-ASSETS> 722,884,342
<PER-SHARE-NAV-BEGIN> 16.61
<PER-SHARE-NII> 0.06
<PER-SHARE-GAIN-APPREC> 0.32
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 16.99
<EXPENSE-RATIO> 0.64
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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 30,1998
and is qualified in its entirety
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 41
<NAME> Balanced Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 558,592,936
<INVESTMENTS-AT-VALUE> 698,694,089
<RECEIVABLES> 3,179,304
<ASSETS-OTHER> 3,145
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 701,876,538
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 580,413
<TOTAL-LIABILITIES> 580,413
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 513,229,858
<SHARES-COMMON-STOCK> 15,698
<SHARES-COMMON-PRIOR> 11,560
<ACCUMULATED-NII-CURRENT> 11,548,538
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 36,416,576
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 140,101,153
<NET-ASSETS> 166,714
<DIVIDEND-INCOME> 970
<INTEREST-INCOME> 2,272
<OTHER-INCOME> 0
<EXPENSES-NET> 978
<NET-INVESTMENT-INCOME> 2,264
<REALIZED-GAINS-CURRENT> 7,233
<APPREC-INCREASE-CURRENT> 277
<NET-CHANGE-FROM-OPS> 9,774
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 15,698
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 9,739
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 6,196,048
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,531,675
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,849,215
<AVERAGE-NET-ASSETS> 164,269
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.14
<PER-SHARE-GAIN-APPREC> 0.48
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.62
<EXPENSE-RATIO> 1.20
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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 30,1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 42
<NAME> Balanced Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 558,592,936
<INVESTMENTS-AT-VALUE> 698,694,089
<RECEIVABLES> 3,179,304
<ASSETS-OTHER> 3,145
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 701,876,538
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 580,413
<TOTAL-LIABILITIES> 580,413
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 513,229,858
<SHARES-COMMON-STOCK> 32,095
<SHARES-COMMON-PRIOR> 23,555
<ACCUMULATED-NII-CURRENT> 2,534,873
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 36,416,576
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 140,101,153
<NET-ASSETS> 341,624
<DIVIDEND-INCOME> 1,961
<INTEREST-INCOME> 4,591
<OTHER-INCOME> 0
<EXPENSES-NET> 1,251
<NET-INVESTMENT-INCOME> 5,301
<REALIZED-GAINS-CURRENT> 14,801
<APPREC-INCREASE-CURRENT> 559
<NET-CHANGE-FROM-OPS> 20,661
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 32,095
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 20,673
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 6,196,048
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,531,675
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,849,215
<AVERAGE-NET-ASSETS> 336,236
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.17
<PER-SHARE-GAIN-APPREC> 0.47
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.64
<EXPENSE-RATIO> 0.75
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 43
<NAME> Balanced Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 558,592,936
<INVESTMENTS-AT-VALUE> 698,694,089
<RECEIVABLES> 3,179,304
<ASSETS-OTHER> 3,145
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 701,876,538
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 580,413
<TOTAL-LIABILITIES> 580,413
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 513,229,858
<SHARES-COMMON-STOCK> 48,412,714
<SHARES-COMMON-PRIOR> 48,223,502
<ACCUMULATED-NII-CURRENT> 2,534,873
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 36,416,576
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 140,101,153
<NET-ASSETS> 700,787,787
<DIVIDEND-INCOME> 4,007,294
<INTEREST-INCOME> 9,380,665
<OTHER-INCOME> 0
<EXPENSES-NET> 1,846,986
<NET-INVESTMENT-INCOME> 11,540,973
<REALIZED-GAINS-CURRENT> 30,198,494
<APPREC-INCREASE-CURRENT> 938,780
<NET-CHANGE-FROM-OPS> 42,678,247
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 8,345,206
<NUMBER-OF-SHARES-REDEEMED> 8,155,994
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 45,652,582
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 6,196,048
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,531,675
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,849,215
<AVERAGE-NET-ASSETS> 685,885,625
<PER-SHARE-NAV-BEGIN> 13.59
<PER-SHARE-NII> 0.24
<PER-SHARE-GAIN-APPREC> 0.65
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 14.48
<EXPENSE-RATIO> 0.54
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 71
<NAME> International Equity Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 577,955,097
<INVESTMENTS-AT-VALUE> 683,754,211
<RECEIVABLES> 30,028,572
<ASSETS-OTHER> 5,908,193
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 719,690,976
<PAYABLE-FOR-SECURITIES> 28,441,719
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 11,362,256
<TOTAL-LIABILITIES> 39,803,975
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 502,731,017
<SHARES-COMMON-STOCK> 12,894
<SHARES-COMMON-PRIOR> 10,526
<ACCUMULATED-NII-CURRENT> 4,698,055
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 66,029,828
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 106,428,101
<NET-ASSETS> 151,581
<DIVIDEND-INCOME> 1,618
<INTEREST-INCOME> 113
<OTHER-INCOME> 0
<EXPENSES-NET> 1,195
<NET-INVESTMENT-INCOME> 536
<REALIZED-GAINS-CURRENT> 11,382
<APPREC-INCREASE-CURRENT> 811
<NET-CHANGE-FROM-OPS> 12,729
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 12,894
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 22,639
<ACCUMULATED-NII-PRIOR> 293,037
<ACCUMULATED-GAINS-PRIOR> (16,328,165)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 2,617,979
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 3,223,516
<AVERAGE-NET-ASSETS> 142,302
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.04
<PER-SHARE-GAIN-APPREC> 1.72
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 11.76
<EXPENSE-RATIO> 1.68
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 72
<NAME> International Equity Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 577,955,097
<INVESTMENTS-AT-VALUE> 683,754,211
<RECEIVABLES> 30,028,572
<ASSETS-OTHER> 5,908,193
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 719,690,976
<PAYABLE-FOR-SECURITIES> 28,441,719
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 11,362,256
<TOTAL-LIABILITIES> 39,803,975
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 502,731,017
<SHARES-COMMON-STOCK> 26,324
<SHARES-COMMON-PRIOR> 21,315
<ACCUMULATED-NII-CURRENT> 4,698,055
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 66,029,828
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 106,428,101
<NET-ASSETS> 310,139
<DIVIDEND-INCOME> 3,315
<INTEREST-INCOME> 232
<OTHER-INCOME> 0
<EXPENSES-NET> 1,793
<NET-INVESTMENT-INCOME> 1,754
<REALIZED-GAINS-CURRENT> 23,310
<APPREC-INCREASE-CURRENT> 1,971
<NET-CHANGE-FROM-OPS> 27,035
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 26,324
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 46,906
<ACCUMULATED-NII-PRIOR> 293,037
<ACCUMULATED-GAINS-PRIOR> (16,328,165)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 2,617,979
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 3,223,516
<AVERAGE-NET-ASSETS> 290,839
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.07
<PER-SHARE-GAIN-APPREC> 1.71
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 11.78
<EXPENSE-RATIO> 1.23
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 73
<NAME> International Equity Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 577,955,097
<INVESTMENTS-AT-VALUE> 683,754,211
<RECEIVABLES> 30,028,572
<ASSETS-OTHER> 5,908,193
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 719,690,976
<PAYABLE-FOR-SECURITIES> 28,441,719
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 11,362,256
<TOTAL-LIABILITIES> 39,803,975
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 502,731,017
<SHARES-COMMON-STOCK> 46,548,897
<SHARES-COMMON-PRIOR> 44,180,338
<ACCUMULATED-NII-CURRENT> 4,698,055
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 66,029,828
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 106,428,101
<NET-ASSETS> 679,425,281
<DIVIDEND-INCOME> 7,124,723
<INTEREST-INCOME> 498,533
<OTHER-INCOME> 0
<EXPENSES-NET> 3,220,528
<NET-INVESTMENT-INCOME> 4,402,728
<REALIZED-GAINS-CURRENT> 49,666,971
<APPREC-INCREASE-CURRENT> 45,496,377
<NET-CHANGE-FROM-OPS> 99,566,076
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,391,363
<NUMBER-OF-SHARES-REDEEMED> 8,022,804
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 132,635,522
<ACCUMULATED-NII-PRIOR> 293,037
<ACCUMULATED-GAINS-PRIOR> (16,328,165)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 2,617,979
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 3,223,516
<AVERAGE-NET-ASSETS> 620,666,803
<PER-SHARE-NAV-BEGIN> 12.38
<PER-SHARE-NII> 0.09
<PER-SHARE-GAIN-APPREC> 2.13
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 14.60
<EXPENSE-RATIO> 1.03
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 21
<NAME> Short Term Bond Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 255,227,178
<INVESTMENTS-AT-VALUE> 256,169,919
<RECEIVABLES> 2,379,348
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 258,549,267
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 269,118
<TOTAL-LIABILITIES> 269,118
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 249,719,758
<SHARES-COMMON-STOCK> 12,238
<SHARES-COMMON-PRIOR> 11,916
<ACCUMULATED-NII-CURRENT> 6,761,363
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 856,287
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 942,741
<NET-ASSETS> 125,745
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 3,899
<OTHER-INCOME> 0
<EXPENSES-NET> 737
<NET-INVESTMENT-INCOME> 3,162
<REALIZED-GAINS-CURRENT> 290
<APPREC-INCREASE-CURRENT> (143)
<NET-CHANGE-FROM-OPS> 3,309
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 12,238
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 3,309
<ACCUMULATED-NII-PRIOR> 61,151
<ACCUMULATED-GAINS-PRIOR> 321,873
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 522,369
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 635,060
<AVERAGE-NET-ASSETS> 124,293
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.26
<PER-SHARE-GAIN-APPREC> 0.01
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.27
<EXPENSE-RATIO> 1.20
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 22
<NAME> Short Term Bond Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 255,227,178
<INVESTMENTS-AT-VALUE> 256,169,919
<RECEIVABLES> 2,379,348
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 258,549,267
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 269,118
<TOTAL-LIABILITIES> 269,118
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 249,719,758
<SHARES-COMMON-STOCK> 25,033
<SHARES-COMMON-PRIOR> 24,328
<ACCUMULATED-NII-CURRENT> 6,761,363
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 856,287
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 942,741
<NET-ASSETS> 257,747
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 7,982
<OTHER-INCOME> 0
<EXPENSES-NET> 940
<NET-INVESTMENT-INCOME> 7,042
<REALIZED-GAINS-CURRENT> 595
<APPREC-INCREASE-CURRENT> (294)
<NET-CHANGE-FROM-OPS> 7,343
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 25,033
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 7,343
<ACCUMULATED-NII-PRIOR> 61,151
<ACCUMULATED-GAINS-PRIOR> 321,873
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 522,369
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 635,060
<AVERAGE-NET-ASSETS> 254,488
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.28
<PER-SHARE-GAIN-APPREC> 0.02
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.30
<EXPENSE-RATIO> 0.74
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
<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, 1998
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 23
<NAME> Short Term Bond Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> Jun-30-1998
<INVESTMENTS-AT-COST> 255,227,178
<INVESTMENTS-AT-VALUE> 256,169,919
<RECEIVABLES> 2,379,348
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 258,549,267
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 269,118
<TOTAL-LIABILITIES> 269,118
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 249,719,758
<SHARES-COMMON-STOCK> 24,468,629
<SHARES-COMMON-PRIOR> 19,577,260
<ACCUMULATED-NII-CURRENT> 6,761,363
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 856,287
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 942,741
<NET-ASSETS> 257,896,657
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 7,323,391
<OTHER-INCOME> 0
<EXPENSES-NET> 633,383
<NET-INVESTMENT-INCOME> 6,690,008
<REALIZED-GAINS-CURRENT> 533,529
<APPREC-INCREASE-CURRENT> (350,161)
<NET-CHANGE-FROM-OPS> 6,873,376
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 8,219,321
<NUMBER-OF-SHARES-REDEEMED> 3,327,952
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 57,628,210
<ACCUMULATED-NII-PRIOR> 61,151
<ACCUMULATED-GAINS-PRIOR> 321,873
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 522,369
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 635,060
<AVERAGE-NET-ASSETS> 233,709,420
<PER-SHARE-NAV-BEGIN> 10.23
<PER-SHARE-NII> 0.30
<PER-SHARE-GAIN-APPREC> 0.01
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.54
<EXPENSE-RATIO> 0.55
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0.00
</TABLE>
