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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 7
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<PAGE> PAGE 8
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<PAGE> PAGE 11
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<PAGE> PAGE 12
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<PAGE> PAGE 13
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<PAGE> PAGE 14
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<PAGE> PAGE 15
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<PAGE> PAGE 16
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<PAGE> PAGE 17
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<PAGE> PAGE 19
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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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<PAGE> PAGE 24
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<PAGE> PAGE 25
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<PAGE> PAGE 26
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<PAGE> PAGE 27
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<PAGE> PAGE 28
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<PAGE> PAGE 29
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<PAGE> PAGE 30
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<PAGE> PAGE 31
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<PAGE> PAGE 32
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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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<PAGE> PAGE 37
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<PAGE> PAGE 38
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070 C020900 N
070 D010900 Y
070 D020900 N
070 E010900 Y
070 E020900 N
070 F010900 Y
070 F020900 N
070 G010900 Y
070 G020900 N
070 H010900 Y
070 H020900 N
070 I010900 N
070 I020900 N
070 J010900 Y
070 J020900 N
070 K010900 Y
<PAGE> PAGE 40
070 K020900 N
070 L010900 Y
070 L020900 Y
070 M010900 Y
070 M020900 Y
070 N010900 Y
070 N020900 N
070 O010900 Y
070 O020900 N
070 P010900 Y
070 P020900 N
070 Q010900 N
070 Q020900 N
070 R010900 Y
070 R020900 N
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071 B000900 5917
071 C000900 24546
071 D000900 24
072 A000900 2
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072 C000900 20
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072 L000900 0
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072 N000900 0
072 O000900 0
072 P000900 0
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072 R000900 1
072 S000900 0
072 T000900 0
072 U000900 0
072 V000900 0
072 W000900 0
072 X000900 36
072 Y000900 0
072 Z000900 14
072AA000900 0
072BB000900 303
072CC010900 1929
072CC020900 0
072DD010900 0
072DD020900 0
<PAGE> PAGE 41
072EE000900 0
073 A010900 0.0000
073 A020900 0.0000
073 B000900 0.0000
073 C000900 0.0000
074 A000900 1073
074 B000900 0
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074 E000900 0
074 F000900 25308
074 G000900 0
074 H000900 0
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074 M000900 0
074 N000900 27141
074 O000900 449
074 P000900 18
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074 R040900 4
074 S000900 0
074 T000900 26670
074 U010900 2473
074 U020900 30
074 V010900 0.00
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074 W000900 0.0000
074 X000900 20
074 Y000900 0
075 A000900 0
075 B000900 25233
076 000900 0.00
008 A001001 MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
008 B001001 A
008 C001001 801-8059
008 D011001 SPRINGFIELD
008 D021001 MA
008 D031001 01111
008 D041001 0001
008 A001002 MILLER ANDERSON & SHERRERD, LLP
008 B001002 S
008 C001002 801-10437
008 D011002 WEST CONSHOHOCKEN
008 D021002 PA
008 D031002 19428
<PAGE> PAGE 42
015 A001001 INVESTORS BANK & TRUST COMPANY
015 B001001 C
015 C011001 BOSTON
015 C021001 MA
015 C031001 02216
015 E011001 X
024 001000 N
028 A011000 0
028 A021000 0
028 A031000 0
028 A041000 0
028 B011000 0
028 B021000 0
028 B031000 0
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028 C011000 0
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028 H001000 0
045 001000 Y
046 001000 N
047 001000 Y
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048 B021000 0.000
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048 F011000 0
<PAGE> PAGE 43
048 F021000 0.000
048 G011000 0
048 G021000 0.000
048 H011000 0
048 H021000 0.000
048 I011000 0
048 I021000 0.000
048 J011000 0
048 J021000 0.000
048 K011000 0
048 K021000 0.000
055 A001000 N
055 B001000 N
056 001000 Y
057 001000 N
062 A001000 N
062 B001000 0.0
062 C001000 0.0
062 D001000 0.0
062 E001000 0.0
062 F001000 0.0
062 G001000 0.0
062 H001000 0.0
062 I001000 0.0
062 J001000 0.0
062 K001000 0.0
062 L001000 0.0
062 M001000 0.0
062 N001000 0.0
062 O001000 0.0
062 P001000 0.0
062 Q001000 0.0
062 R001000 0.0
066 A001000 Y
066 D001000 Y
067 001000 N
068 A001000 N
068 B001000 N
069 001000 N
070 A011000 Y
070 A021000 Y
070 B011000 Y
070 B021000 N
070 C011000 Y
070 C021000 N
070 D011000 Y
070 D021000 N
070 E011000 Y
070 E021000 N
070 F011000 Y
070 F021000 N
<PAGE> PAGE 44
070 G011000 Y
070 G021000 N
070 H011000 Y
070 H021000 N
070 I011000 N
070 I021000 N
070 J011000 Y
070 J021000 N
070 K011000 Y
070 K021000 N
070 L011000 Y
070 L021000 Y
070 M011000 Y
070 M021000 N
070 N011000 Y
070 N021000 N
070 O011000 Y
070 O021000 N
070 P011000 Y
070 P021000 N
070 Q011000 N
070 Q021000 N
070 R011000 Y
070 R021000 N
071 A001000 29278
071 B001000 5157
071 C001000 24181
071 D001000 21
072 A001000 2
072 B001000 17
072 C001000 13
072 D001000 0
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072 F001000 28
072 G001000 4
072 H001000 0
072 I001000 0
072 J001000 0
072 K001000 0
072 L001000 0
072 M001000 3
072 N001000 0
072 O001000 0
072 P001000 0
072 Q001000 0
072 R001000 1
072 S001000 0
072 T001000 0
072 U001000 0
072 V001000 0
072 W001000 0
<PAGE> PAGE 45
072 X001000 36
072 Y001000 0
072 Z001000 -6
072AA001000 0
072BB001000 187
072CC011000 1008
072CC021000 0
072DD011000 0
072DD021000 0
072EE001000 0
073 A011000 0.0000
073 A021000 0.0000
073 B001000 0.0000
073 C001000 0.0000
074 A001000 1404
074 B001000 0
074 C001000 0
074 D001000 0
074 E001000 0
074 F001000 24755
074 G001000 0
074 H001000 0
074 I001000 0
074 J001000 744
074 K001000 0
074 L001000 13
074 M001000 0
074 N001000 26915
074 O001000 1074
074 P001000 18
074 Q001000 0
074 R011000 0
074 R021000 0
074 R031000 0
074 R041000 3
074 S001000 0
074 T001000 25820
074 U011000 2470
074 U021000 30
074 V011000 0.00
074 V021000 0.00
074 W001000 0.0000
074 X001000 20
074 Y001000 0
075 A001000 0
075 B001000 24698
076 001000 0.00
008 A001101 MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
008 B001101 A
008 C001101 801-8059
008 D011101 SPRINGFIELD
<PAGE> PAGE 46
008 D021101 MA
008 D031101 01111
008 D041101 0001
008 A001102 J.P. MORGAN INVESTMENT MANAGEMENT INC.
008 B001102 S
008 C001102 801-21011
008 D011102 NEW YORK
008 D021102 NY
008 D031102 10036
008 A001103 WADDELL & REED INVESTMENT MANAGEMENT COMPANY
008 B001103 S
008 C001103 801-40372
008 D011103 OVERLAND PARK
008 D021103 KS
008 D031103 66202
015 A001101 INVESTORS BANK & TRUST COMPANY
015 B001101 C
015 C011101 BOSTON
015 C021101 MA
015 C031101 02116
015 E011101 X
024 001100 N
028 A011100 0
028 A021100 0
028 A031100 0
028 A041100 0
028 B011100 0
028 B021100 0
028 B031100 0
028 B041100 0
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028 E021100 0
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028 G021100 0
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<PAGE> PAGE 47
045 001100 Y
046 001100 N
047 001100 Y
048 001100 0.820
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048 B021100 0.000
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048 I021100 0.000
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048 K011100 0
048 K021100 0.000
055 A001100 N
055 B001100 N
056 001100 Y
057 001100 N
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062 D001100 0.0
062 E001100 0.0
062 F001100 0.0
062 G001100 0.0
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062 K001100 0.0
062 L001100 0.0
062 M001100 0.0
062 N001100 0.0
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062 P001100 0.0
062 Q001100 0.0
062 R001100 0.0
066 A001100 Y
066 B001100 Y
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<PAGE> PAGE 48
068 A001100 N
068 B001100 N
069 001100 N
070 A011100 Y
070 A021100 Y
070 B011100 Y
070 B021100 N
070 C011100 Y
070 C021100 N
070 D011100 Y
070 D021100 N
070 E011100 Y
070 E021100 N
070 F011100 Y
070 F021100 N
070 G011100 Y
070 G021100 N
070 H011100 Y
070 H021100 N
070 I011100 N
070 I021100 N
070 J011100 Y
070 J021100 N
070 K011100 Y
070 K021100 N
070 L011100 Y
070 L021100 Y
070 M011100 Y
070 M021100 N
070 N011100 Y
070 N021100 N
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070 O021100 N
070 P011100 Y
070 P021100 N
070 Q011100 N
070 Q021100 N
070 R011100 Y
070 R021100 N
071 A001100 23470
071 B001100 4208
071 C001100 21576
071 D001100 20
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072 C001100 12
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072 G001100 5
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<PAGE> PAGE 49
072 I001100 0
072 J001100 0
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072 N001100 0
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072 R001100 1
072 S001100 0
072 T001100 0
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072 X001100 43
072 Y001100 0
072 Z001100 25
072AA001100 181
072BB001100 0
072CC011100 2111
072CC021100 0
072DD011100 0
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072EE001100 0
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073 A021100 0.0000
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074 F001100 21546
074 G001100 0
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074 O001100 558
074 P001100 22
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<PAGE> PAGE 50
074 T001100 27321
074 U011100 2470
074 U021100 30
074 V011100 0.00
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076 001100 0.00
008 A001201 MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
008 B001201 A
008 C001201 801-8059
008 D011201 SPRINGFIELD
008 D021201 MA
008 D031201 01111
008 D041201 0001
015 A001201 INVESTORS BANK & TRUST COMPANY
015 B001201 C
015 C011201 BOSTON
015 C021201 MA
015 C031201 02116
015 E011201 X
024 001200 N
028 A011200 0
028 A021200 0
028 A031200 0
028 A041200 0
028 B011200 0
028 B021200 0
028 B031200 0
028 B041200 0
028 C011200 0
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028 C031200 0
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<PAGE> PAGE 51
028 G031200 0
028 G041200 300
028 H001200 0
045 001200 Y
046 001200 N
047 001200 Y
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055 A001200 N
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062 H001200 0.0
062 I001200 12.2
062 J001200 0.0
062 K001200 0.0
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062 N001200 39.5
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<PAGE> PAGE 52
063 A001200 0
063 B001200 6.8
066 A001200 N
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068 A001200 N
068 B001200 N
069 001200 N
070 A011200 Y
070 A021200 Y
070 B011200 Y
070 B021200 N
070 C011200 Y
070 C021200 N
070 D011200 Y
070 D021200 N
070 E011200 Y
070 E021200 N
070 F011200 Y
070 F021200 N
070 G011200 Y
070 G021200 N
070 H011200 Y
070 H021200 N
070 I011200 N
070 I021200 N
070 J011200 Y
070 J021200 Y
070 K011200 Y
070 K021200 N
070 L011200 Y
070 L021200 Y
070 M011200 Y
070 M021200 N
070 N011200 Y
070 N021200 N
070 O011200 Y
070 O021200 N
070 P011200 Y
070 P021200 N
070 Q011200 N
070 Q021200 N
070 R011200 Y
070 R021200 N
071 A001200 27967
071 B001200 5947
071 C001200 23460
071 D001200 25
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<PAGE> PAGE 53
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072 R001200 1
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072 Z001200 236
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072BB001200 89
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072CC021200 420
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072DD021200 0
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073 A011200 0.0000
073 A021200 0.0000
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074 D001200 21511
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074 L001200 226
074 M001200 0
074 N001200 24749
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<PAGE> PAGE 54
074 R021200 0
074 R031200 0
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074 T001200 24731
074 U011200 2470
074 U021200 30
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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, 1999
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-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 278,539,449
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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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 012
<NAME> Prime Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 278,539,449
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<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 273,450,481
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<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 5,549,133
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (23,224)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (42,877)
<NET-ASSETS> 101,754
<DIVIDEND-INCOME> 0
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<OTHER-INCOME> 0
<EXPENSES-NET> 113
<NET-INVESTMENT-INCOME> 755
<REALIZED-GAINS-CURRENT> 0
<APPREC-INCREASE-CURRENT> (20)
<NET-CHANGE-FROM-OPS> 735
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<NUMBER-OF-SHARES-SOLD> 660
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<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 101,754
<ACCUMULATED-NII-PRIOR> 19,112
<ACCUMULATED-GAINS-PRIOR> (20,684)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 488,133
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 605,468
<AVERAGE-NET-ASSETS> 101,390
<PER-SHARE-NAV-BEGIN> 152.99
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<PER-SHARE-GAIN-APPREC> (0.03)
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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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 013
<NAME> Prime Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 278,539,449
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<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (42,877)
<NET-ASSETS> 1,977,082
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 26,203
<OTHER-INCOME> 0
<EXPENSES-NET> 2,783
<NET-INVESTMENT-INCOME> 23,420
<REALIZED-GAINS-CURRENT> (13)
<APPREC-INCREASE-CURRENT> (419)
<NET-CHANGE-FROM-OPS> 22,988
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 153,891
<NUMBER-OF-SHARES-REDEEMED> 144,760
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 1,421,002
<ACCUMULATED-NII-PRIOR> 19,112
<ACCUMULATED-GAINS-PRIOR> (20,684)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 488,133
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 605,468
<AVERAGE-NET-ASSETS> 1,012,507
<PER-SHARE-NAV-BEGIN> 150.73
<PER-SHARE-NII> 3.54
<PER-SHARE-GAIN-APPREC> (0.05)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 154.22
<EXPENSE-RATIO> 0.55
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 014
<NAME> Prime Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 278,539,449
<INVESTMENTS-AT-VALUE> 278,496,572
<RECEIVABLES> 3,751,363
<ASSETS-OTHER> 7,098
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 282,255,033
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3,321,520
<TOTAL-LIABILITIES> 3,321,520
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 273,450,481
<SHARES-COMMON-STOCK> 1,794,019
<SHARES-COMMON-PRIOR> 1,670,110
<ACCUMULATED-NII-CURRENT> 5,549,133
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (23,224)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (42,877)
<NET-ASSETS> 276,731,553
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 6,105,277
<OTHER-INCOME> 0
<EXPENSES-NET> 601,899
<NET-INVESTMENT-INCOME> 5,503,378
<REALIZED-GAINS-CURRENT> (2,526)
<APPREC-INCREASE-CURRENT> (83,298)
<NET-CHANGE-FROM-OPS> 5,417,554
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 3,286,786
<NUMBER-OF-SHARES-REDEEMED> 3,162,877
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 24,974,838
<ACCUMULATED-NII-PRIOR> 19,112
<ACCUMULATED-GAINS-PRIOR> (20,684)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 488,133
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 605,468
<AVERAGE-NET-ASSETS> 234,878,801
<PER-SHARE-NAV-BEGIN> 150.74
<PER-SHARE-NII> 3.57
<PER-SHARE-GAIN-APPREC> (0.06)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 154.25
<EXPENSE-RATIO> 0.52
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 021
<NAME> Short Term Bond Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 242,354,199
<INVESTMENTS-AT-VALUE> 241,722,646
<RECEIVABLES> 1,811,636
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 3,479
<TOTAL-ASSETS> 243,537,761
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 10,640,394
<TOTAL-LIABILITIES> 10,640,394
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 226,266,704
<SHARES-COMMON-STOCK> 12,638
<SHARES-COMMON-PRIOR> 12,541
<ACCUMULATED-NII-CURRENT> 6,959,536
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 302,680
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (631,553)
<NET-ASSETS> 131,856
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 3,747
<OTHER-INCOME> 0
<EXPENSES-NET> 730
<NET-INVESTMENT-INCOME> 3,017
<REALIZED-GAINS-CURRENT> 184
<APPREC-INCREASE-CURRENT> (1,700)
<NET-CHANGE-FROM-OPS> 1,501
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 97
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 2,502
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (75,661)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 577,414
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 722,753
<AVERAGE-NET-ASSETS> 130,497
<PER-SHARE-NAV-BEGIN> 10.31
<PER-SHARE-NII> 0.24
<PER-SHARE-GAIN-APPREC> (0.12)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.43
<EXPENSE-RATIO> 1.13
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 022
<NAME> Short Term Bond Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 242,354,199
<INVESTMENTS-AT-VALUE> 241,722,646
<RECEIVABLES> 1,811,636
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 3,479
<TOTAL-ASSETS> 243,537,761
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 10,640,394
<TOTAL-LIABILITIES> 10,640,394
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 226,266,704
<SHARES-COMMON-STOCK> 9,783
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 6,959,536
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 302,680
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (631,553)
<NET-ASSETS> 102,074
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 933
<OTHER-INCOME> 0
<EXPENSES-NET> 120
<NET-INVESTMENT-INCOME> 813
<REALIZED-GAINS-CURRENT> 19
<APPREC-INCREASE-CURRENT> (698)
<NET-CHANGE-FROM-OPS> 134
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 9,783
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 102,074
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (75,661)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 577,414
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 722,753
<AVERAGE-NET-ASSETS> 101,758
<PER-SHARE-NAV-BEGIN> 10.42
<PER-SHARE-NII> 0.09
<PER-SHARE-GAIN-APPREC> (0.08)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.43
<EXPENSE-RATIO> 0.71
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 023
<NAME> Short Term Bond Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 242,354,199
<INVESTMENTS-AT-VALUE> 241,722,646
<RECEIVABLES> 1,811,636
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 3,479
<TOTAL-ASSETS> 243,537,761
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 10,640,394
<TOTAL-LIABILITIES> 10,640,394
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 226,266,704
<SHARES-COMMON-STOCK> 16,754
<SHARES-COMMON-PRIOR> 26,073
<ACCUMULATED-NII-CURRENT> 6,959,536
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 302,680
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (631,553)
<NET-ASSETS> 175,106
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 7,151
<OTHER-INCOME> 0
<EXPENSES-NET> 782
<NET-INVESTMENT-INCOME> 6,369
<REALIZED-GAINS-CURRENT> 388
<APPREC-INCREASE-CURRENT> (3,005)
<NET-CHANGE-FROM-OPS> 3,752
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 2,338
<NUMBER-OF-SHARES-REDEEMED> 11,657
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> (93,678)
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (75,661)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 577,414
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 722,753
<AVERAGE-NET-ASSETS> 250,691
<PER-SHARE-NAV-BEGIN> 10.31
<PER-SHARE-NII> 0.39
<PER-SHARE-GAIN-APPREC> (0.25)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.45
<EXPENSE-RATIO> 0.63
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 024
<NAME> Short Term Bond Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 242,354,199
<INVESTMENTS-AT-VALUE> 241,722,646
<RECEIVABLES> 1,811,636
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 3,479
<TOTAL-ASSETS> 243,537,761
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 10,640,394
<TOTAL-LIABILITIES> 10,640,394
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 226,266,704
<SHARES-COMMON-STOCK> 22,239,465
<SHARES-COMMON-PRIOR> 27,529,935
<ACCUMULATED-NII-CURRENT> 6,959,536
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 302,680
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (631,553)
<NET-ASSETS> 232,488,331
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 7,670,458
<OTHER-INCOME> 0
<EXPENSES-NET> 721,121
<NET-INVESTMENT-INCOME> 6,949,337
<REALIZED-GAINS-CURRENT> 377,750
<APPREC-INCREASE-CURRENT> (3,470,910)
<NET-CHANGE-FROM-OPS> 3,856,177
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 2,891,193
<NUMBER-OF-SHARES-REDEEMED> 8,181,663
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> (51,184,863)
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (75,661)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 577,414
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 722,753
<AVERAGE-NET-ASSETS> 267,491,700
<PER-SHARE-NAV-BEGIN> 10.30
<PER-SHARE-NII> 0.31
<PER-SHARE-GAIN-APPREC> (0.16)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.45
<EXPENSE-RATIO> 0.54
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 031
<NAME> Core Bond Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 756,488,411
<INVESTMENTS-AT-VALUE> 747,246,323
<RECEIVABLES> 14,989,008
<ASSETS-OTHER> 19,759
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 762,255,090
<PAYABLE-FOR-SECURITIES> 3,661,612
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 113,329,501
<TOTAL-LIABILITIES> 116,991,113
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 637,725,924
<SHARES-COMMON-STOCK> 12,865
<SHARES-COMMON-PRIOR> 12,774
<ACCUMULATED-NII-CURRENT> 18,941,509
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (2,161,368)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (9,242,088)
<NET-ASSETS> 138,841
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 4,495
<OTHER-INCOME> 0
<EXPENSES-NET> 796
<NET-INVESTMENT-INCOME> 3,699
<REALIZED-GAINS-CURRENT> (595)
<APPREC-INCREASE-CURRENT> (6,579)
<NET-CHANGE-FROM-OPS> (3,475)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 91
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> (2,474)
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 493,441
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,472,160
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,787,301
<AVERAGE-NET-ASSETS> 139,869
<PER-SHARE-NAV-BEGIN> 11.06
<PER-SHARE-NII> 0.29
<PER-SHARE-GAIN-APPREC> (0.56)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.79
<EXPENSE-RATIO> 1.15
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 032
<NAME> Core Bond Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 756,488,411
<INVESTMENTS-AT-VALUE> 747,246,323
<RECEIVABLES> 14,989,008
<ASSETS-OTHER> 19,759
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 762,255,090
<PAYABLE-FOR-SECURITIES> 3,661,612
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 113,329,501
<TOTAL-LIABILITIES> 116,991,113
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 637,725,924
<SHARES-COMMON-STOCK> 9,315
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 18,941,509
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (2,161,368)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (9,242,088)
<NET-ASSETS> 100,618
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 1,047
<OTHER-INCOME> 0
<EXPENSES-NET> 127
<NET-INVESTMENT-INCOME> 920
<REALIZED-GAINS-CURRENT> (482)
<APPREC-INCREASE-CURRENT> (2,000)
<NET-CHANGE-FROM-OPS> (1,562)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 9,315
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 100,618
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 493,441
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,472,160
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,787,301
<AVERAGE-NET-ASSETS> 100,626
<PER-SHARE-NAV-BEGIN> 10.97
<PER-SHARE-NII> 0.10
<PER-SHARE-GAIN-APPREC> (0.27)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.80
<EXPENSE-RATIO> 0.76
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 033
<NAME> Core Bond Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 756,488,411
<INVESTMENTS-AT-VALUE> 747,246,323
<RECEIVABLES> 14,989,008
<ASSETS-OTHER> 19,759
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 762,255,090
<PAYABLE-FOR-SECURITIES> 3,661,612
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 113,329,501
<TOTAL-LIABILITIES> 116,991,113
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 637,725,924
<SHARES-COMMON-STOCK> 102,178
<SHARES-COMMON-PRIOR> 36,181
<ACCUMULATED-NII-CURRENT> 18,941,509
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (2,161,368)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (9,242,088)
<NET-ASSETS> 1,104,040
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 26,336
<OTHER-INCOME> 0
<EXPENSES-NET> 2,615
<NET-INVESTMENT-INCOME> 23,721
<REALIZED-GAINS-CURRENT> (4,463)
<APPREC-INCREASE-CURRENT> (36,767)
<NET-CHANGE-FROM-OPS> (17,509)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 78,141
<NUMBER-OF-SHARES-REDEEMED> 12,144
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 703,984
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 493,441
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,472,160
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,787,301
<AVERAGE-NET-ASSETS> 815,079
<PER-SHARE-NAV-BEGIN> 11.06
<PER-SHARE-NII> 0.28
<PER-SHARE-GAIN-APPREC> (0.53)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.81
<EXPENSE-RATIO> 0.65
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 034
<NAME> Core Bond Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 756,488,411
<INVESTMENTS-AT-VALUE> 747,246,323
<RECEIVABLES> 14,989,008
<ASSETS-OTHER> 19,759
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 762,255,090
<PAYABLE-FOR-SECURITIES> 3,661,612
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 113,329,501
<TOTAL-LIABILITIES> 116,991,113
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 637,725,924
<SHARES-COMMON-STOCK> 59,562,818
<SHARES-COMMON-PRIOR> 64,158,721
<ACCUMULATED-NII-CURRENT> 18,941,509
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (2,161,368)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (9,242,088)
<NET-ASSETS> 643,920,478
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 20,696,932
<OTHER-INCOME> 0
<EXPENSES-NET> 1,783,763
<NET-INVESTMENT-INCOME> 18,913,169
<REALIZED-GAINS-CURRENT> (2,649,269)
<APPREC-INCREASE-CURRENT> (30,531,777)
<NET-CHANGE-FROM-OPS> (14,267,877)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 15,058,722
<NUMBER-OF-SHARES-REDEEMED> 19,654,625
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> (65,539,009)
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 493,441
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,472,160
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1,787,301
<AVERAGE-NET-ASSETS> 645,139,873
<PER-SHARE-NAV-BEGIN> 11.06
<PER-SHARE-NII> 0.32
<PER-SHARE-GAIN-APPREC> (0.57)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.81
<EXPENSE-RATIO> 0.56
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 041
<NAME> Balanced Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 711,133,681
<INVESTMENTS-AT-VALUE> 893,047,808
<RECEIVABLES> 4,219,745
<ASSETS-OTHER> 320
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 897,267,873
<PAYABLE-FOR-SECURITIES> 547,056
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 55,555,307
<TOTAL-LIABILITIES> 56,102,363
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 635,991,616
<SHARES-COMMON-STOCK> 12,534
<SHARES-COMMON-PRIOR> 12,465
<ACCUMULATED-NII-CURRENT> 13,136,329
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 10,207,660
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 181,829,905
<NET-ASSETS> 184,437
<DIVIDEND-INCOME> 937
<INTEREST-INCOME> 2,456
<OTHER-INCOME> 0
<EXPENSES-NET> 1,040
<NET-INVESTMENT-INCOME> 2,353
<REALIZED-GAINS-CURRENT> 400
<APPREC-INCREASE-CURRENT> 3,673
<NET-CHANGE-FROM-OPS> 6,426
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 69
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 7,427
<ACCUMULATED-NII-PRIOR> 32,992
<ACCUMULATED-GAINS-PRIOR> 8,384,459
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,836,957
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,255,270
<AVERAGE-NET-ASSETS> 178,011
<PER-SHARE-NAV-BEGIN> 14.20
<PER-SHARE-NII> 0.19
<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> 14.71
<EXPENSE-RATIO> 1.18
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 042
<NAME> Balanced Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 711,133,681
<INVESTMENTS-AT-VALUE> 893,047,808
<RECEIVABLES> 4,219,745
<ASSETS-OTHER> 320
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 897,267,873
<PAYABLE-FOR-SECURITIES> 547,056
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 55,555,307
<TOTAL-LIABILITIES> 56,102,363
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 635,991,616
<SHARES-COMMON-STOCK> 6,908
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 13,136,329
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 10,207,660
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 181,829,905
<NET-ASSETS> 101,825
<DIVIDEND-INCOME> 558
<INTEREST-INCOME> 1,462
<OTHER-INCOME> 0
<EXPENSES-NET> 144
<NET-INVESTMENT-INCOME> 1,876
<REALIZED-GAINS-CURRENT> 103
<APPREC-INCREASE-CURRENT> (1,154)
<NET-CHANGE-FROM-OPS> 825
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 6,908
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 101,825
<ACCUMULATED-NII-PRIOR> 32,992
<ACCUMULATED-GAINS-PRIOR> 8,384,459
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,836,957
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,255,270
<AVERAGE-NET-ASSETS> 101,111
<PER-SHARE-NAV-BEGIN> 14.62
<PER-SHARE-NII> 0.07
<PER-SHARE-GAIN-APPREC> 0.05
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 14.74
<EXPENSE-RATIO> 0.91
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 043
<NAME> Balanced Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 711,133,681
<INVESTMENTS-AT-VALUE> 893,047,808
<RECEIVABLES> 4,219,745
<ASSETS-OTHER> 320
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 897,267,873
<PAYABLE-FOR-SECURITIES> 547,056
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 55,555,307
<TOTAL-LIABILITIES> 56,102,363
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 635,991,616
<SHARES-COMMON-STOCK> 4,278,711
<SHARES-COMMON-PRIOR> 74,030
<ACCUMULATED-NII-CURRENT> 13,136,329
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 10,207,660
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 181,829,905
<NET-ASSETS> 63,067,310
<DIVIDEND-INCOME> 249,719
<INTEREST-INCOME> 654,720
<OTHER-INCOME> 0
<EXPENSES-NET> 173,376
<NET-INVESTMENT-INCOME> 731,063
<REALIZED-GAINS-CURRENT> 128,368
<APPREC-INCREASE-CURRENT> 2,358,542
<NET-CHANGE-FROM-OPS> 3,217,973
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 4,213,335
<NUMBER-OF-SHARES-REDEEMED> 8,654
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 62,016,054
<ACCUMULATED-NII-PRIOR> 32,992
<ACCUMULATED-GAINS-PRIOR> 8,384,459
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,836,957
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,255,270
<AVERAGE-NET-ASSETS> 46,621,336
<PER-SHARE-NAV-BEGIN> 14.20
<PER-SHARE-NII> 0.22
<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> 14.74
<EXPENSE-RATIO> 0.75
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 044
<NAME> Balanced Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 711,133,681
<INVESTMENTS-AT-VALUE> 893,047,808
<RECEIVABLES> 4,219,745
<ASSETS-OTHER> 320
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 897,267,873
<PAYABLE-FOR-SECURITIES> 547,056
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 55,555,307
<TOTAL-LIABILITIES> 56,102,363
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 635,991,616
<SHARES-COMMON-STOCK> 52,710,856
<SHARES-COMMON-PRIOR> 54,365,582
<ACCUMULATED-NII-CURRENT> 13,136,329
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 10,207,660
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 181,829,905
<NET-ASSETS> 777,811,938
<DIVIDEND-INCOME> 3,989,359
<INTEREST-INCOME> 10,459,396
<OTHER-INCOME> 0
<EXPENSES-NET> 2,080,710
<NET-INVESTMENT-INCOME> 12,368,045
<REALIZED-GAINS-CURRENT> 1,694,330
<APPREC-INCREASE-CURRENT> 15,367,821
<NET-CHANGE-FROM-OPS> 29,430,196
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 9,146,316
<NUMBER-OF-SHARES-REDEEMED> 10,801,042
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 6,048,585
<ACCUMULATED-NII-PRIOR> 32,992
<ACCUMULATED-GAINS-PRIOR> 8,384,459
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,836,957
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,255,270
<AVERAGE-NET-ASSETS> 758,325,898
<PER-SHARE-NAV-BEGIN> 14.20
<PER-SHARE-NII> 0.23
<PER-SHARE-GAIN-APPREC> 0.33
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 14.76
<EXPENSE-RATIO> 0.55
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 051
<NAME> Core Equity Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 2,155,710,411
<INVESTMENTS-AT-VALUE> 3,685,544,716
<RECEIVABLES> 37,700,369
<ASSETS-OTHER> 1,478
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 3,723,246,563
<PAYABLE-FOR-SECURITIES> 12,203,540
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 131,403,557
<TOTAL-LIABILITIES> 143,607,097
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,900,313,829
<SHARES-COMMON-STOCK> 12,406
<SHARES-COMMON-PRIOR> 12,354
<ACCUMULATED-NII-CURRENT> 25,656,687
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 123,834,645
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,529,834,305
<NET-ASSETS> 244,669
<DIVIDEND-INCOME> 2,283
<INTEREST-INCOME> 48
<OTHER-INCOME> 0
<EXPENSES-NET> 1,318
<NET-INVESTMENT-INCOME> 1,013
<REALIZED-GAINS-CURRENT> 6,821
<APPREC-INCREASE-CURRENT> 8,493
<NET-CHANGE-FROM-OPS> 16,327
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 52
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 17,327
<ACCUMULATED-NII-PRIOR> 106,352
<ACCUMULATED-GAINS-PRIOR> 21,039,858
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 7,987,925
<INTEREST-EXPENSE> 9,036
<GROSS-EXPENSE> 9,448,964
<AVERAGE-NET-ASSETS> 229,530
<PER-SHARE-NAV-BEGIN> 18.40
<PER-SHARE-NII> 0.08
<PER-SHARE-GAIN-APPREC> 1.24
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 19.72
<EXPENSE-RATIO> 1.16
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 052
<NAME> Core Equity Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 2,155,710,411
<INVESTMENTS-AT-VALUE> 3,685,544,716
<RECEIVABLES> 37,700,369
<ASSETS-OTHER> 1,478
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 3,723,246,563
<PAYABLE-FOR-SECURITIES> 12,203,540
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 131,403,557
<TOTAL-LIABILITIES> 143,607,097
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,900,313,829
<SHARES-COMMON-STOCK> 5,268
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 25,656,687
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 123,834,645
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,529,834,305
<NET-ASSETS> 104,094
<DIVIDEND-INCOME> 2,905
<INTEREST-INCOME> 61
<OTHER-INCOME> 0
<EXPENSES-NET> 141
<NET-INVESTMENT-INCOME> 2,825
<REALIZED-GAINS-CURRENT> 710
<APPREC-INCREASE-CURRENT> (1,446)
<NET-CHANGE-FROM-OPS> 2,089
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 5,268
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 104,094
<ACCUMULATED-NII-PRIOR> 106,352
<ACCUMULATED-GAINS-PRIOR> 21,039,858
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 7,987,925
<INTEREST-EXPENSE> 9,036
<GROSS-EXPENSE> 9,448,964
<AVERAGE-NET-ASSETS> 102,770
<PER-SHARE-NAV-BEGIN> 19.36
<PER-SHARE-NII> 0.05
<PER-SHARE-GAIN-APPREC> 0.35
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 19.76
<EXPENSE-RATIO> 0.85
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 053
<NAME> Core Equity Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 2,155,710,411
<INVESTMENTS-AT-VALUE> 3,685,544,716
<RECEIVABLES> 37,700,369
<ASSETS-OTHER> 1,478
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 3,723,246,563
<PAYABLE-FOR-SECURITIES> 12,203,540
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 131,403,557
<TOTAL-LIABILITIES> 143,607,097
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,900,313,829
<SHARES-COMMON-STOCK> 111,112
<SHARES-COMMON-PRIOR> 40,993
<ACCUMULATED-NII-CURRENT> 25,656,687
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 123,834,645
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,529,834,305
<NET-ASSETS> 2,195,170
<DIVIDEND-INCOME> 10,101
<INTEREST-INCOME> 213
<OTHER-INCOME> 0
<EXPENSES-NET> 3,679
<NET-INVESTMENT-INCOME> 6,635
<REALIZED-GAINS-CURRENT> 32,023
<APPREC-INCREASE-CURRENT> 51,128
<NET-CHANGE-FROM-OPS> 89,786
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 77,174
<NUMBER-OF-SHARES-REDEEMED> 7,055
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 1,441,116
<ACCUMULATED-NII-PRIOR> 106,352
<ACCUMULATED-GAINS-PRIOR> 21,039,858
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 7,987,925
<INTEREST-EXPENSE> 9,036
<GROSS-EXPENSE> 9,448,964
<AVERAGE-NET-ASSETS> 1,026,437
<PER-SHARE-NAV-BEGIN> 18.39
<PER-SHARE-NII> 0.27
<PER-SHARE-GAIN-APPREC> 1.10
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 19.76
<EXPENSE-RATIO> 0.72
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 054
<NAME> Core Equity Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 2,155,710,411
<INVESTMENTS-AT-VALUE> 3,685,544,716
<RECEIVABLES> 37,700,369
<ASSETS-OTHER> 1,478
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 3,723,246,563
<PAYABLE-FOR-SECURITIES> 12,203,540
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 131,403,557
<TOTAL-LIABILITIES> 143,607,097
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,900,313,829
<SHARES-COMMON-STOCK> 180,921,712
<SHARES-COMMON-PRIOR> 194,978,032
<ACCUMULATED-NII-CURRENT> 25,656,687
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 123,834,645
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,529,834,305
<NET-ASSETS> 3,577,095,533
<DIVIDEND-INCOME> 34,269,788
<INTEREST-INCOME> 722,934
<OTHER-INCOME> 0
<EXPENSES-NET> 9,452,862
<NET-INVESTMENT-INCOME> 25,539,860
<REALIZED-GAINS-CURRENT> 102,755,234
<APPREC-INCREASE-CURRENT> 118,620,105
<NET-CHANGE-FROM-OPS> 246,915,199
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 20,313,758
<NUMBER-OF-SHARES-REDEEMED> 34,370,078
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> (9,081,953)
<ACCUMULATED-NII-PRIOR> 106,352
<ACCUMULATED-GAINS-PRIOR> 21,039,858
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 7,987,925
<INTEREST-EXPENSE> 9,036
<GROSS-EXPENSE> 9,448,964
<AVERAGE-NET-ASSETS> 3,449,870,558
<PER-SHARE-NAV-BEGIN> 18.39
<PER-SHARE-NII> 0.14
<PER-SHARE-GAIN-APPREC> 1.24
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 19.77
<EXPENSE-RATIO> 0.55
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 061
<NAME> Small CAP Value Equity Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 574,291,070
<INVESTMENTS-AT-VALUE> 721,952,625
<RECEIVABLES> 3,005,413
<ASSETS-OTHER> 284
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 724,958,322
<PAYABLE-FOR-SECURITIES> 5,430,443
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 18,222,684
<TOTAL-LIABILITIES> 23,653,127
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 545,984,034
<SHARES-COMMON-STOCK> 12,438
<SHARES-COMMON-PRIOR> 12,364
<ACCUMULATED-NII-CURRENT> 3,722,927
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 3,936,679
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 147,661,555
<NET-ASSETS> 183,478
<DIVIDEND-INCOME> 1,046
<INTEREST-INCOME> 415
<OTHER-INCOME> 0
<EXPENSES-NET> 1,036
<NET-INVESTMENT-INCOME> 425
<REALIZED-GAINS-CURRENT> 827
<APPREC-INCREASE-CURRENT> 7,278
<NET-CHANGE-FROM-OPS> 8,530
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 74
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 9,530
<ACCUMULATED-NII-PRIOR> 126,877
<ACCUMULATED-GAINS-PRIOR> 658,938
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,802,863
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,107,064
<AVERAGE-NET-ASSETS> 166,175
<PER-SHARE-NAV-BEGIN> 14.07
<PER-SHARE-NII> 0.03
<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> 14.75
<EXPENSE-RATIO> 1.26
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 062
<NAME> Small CAP Value Equity Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 574,291,070
<INVESTMENTS-AT-VALUE> 721,952,625
<RECEIVABLES> 3,005,413
<ASSETS-OTHER> 284
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 724,958,322
<PAYABLE-FOR-SECURITIES> 5,430,443
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 18,222,684
<TOTAL-LIABILITIES> 23,653,127
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 545,984,034
<SHARES-COMMON-STOCK> 7,451
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 3,722,927
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 3,936,679
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 147,661,555
<NET-ASSETS> 110,050
<DIVIDEND-INCOME> 527
<INTEREST-INCOME> 209
<OTHER-INCOME> 0
<EXPENSES-NET> 156
<NET-INVESTMENT-INCOME> 580
<REALIZED-GAINS-CURRENT> (608)
<APPREC-INCREASE-CURRENT> 8,297
<NET-CHANGE-FROM-OPS> 8,269
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 7,451
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 110,050
<ACCUMULATED-NII-PRIOR> 126,877
<ACCUMULATED-GAINS-PRIOR> 658,938
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,802,863
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,107,064
<AVERAGE-NET-ASSETS> 104,967
<PER-SHARE-NAV-BEGIN> 13.66
<PER-SHARE-NII> 0.02
<PER-SHARE-GAIN-APPREC> 1.09
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 14.77
<EXPENSE-RATIO> 0.95
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 063
<NAME> Small CAP Value Equity Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 574,291,070
<INVESTMENTS-AT-VALUE> 721,952,625
<RECEIVABLES> 3,005,413
<ASSETS-OTHER> 284
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 724,958,322
<PAYABLE-FOR-SECURITIES> 5,430,443
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 18,222,684
<TOTAL-LIABILITIES> 23,653,127
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 545,984,034
<SHARES-COMMON-STOCK> 56,310
<SHARES-COMMON-PRIOR> 40,399
<ACCUMULATED-NII-CURRENT> 3,722,927
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 3,936,679
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 147,661,555
<NET-ASSETS> 832,030
<DIVIDEND-INCOME> 4,325
<INTEREST-INCOME> 1,718
<OTHER-INCOME> 0
<EXPENSES-NET> 2,825
<NET-INVESTMENT-INCOME> 3,218
<REALIZED-GAINS-CURRENT> 2,243
<APPREC-INCREASE-CURRENT> 63,770
<NET-CHANGE-FROM-OPS> 69,231
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 30,819
<NUMBER-OF-SHARES-REDEEMED> 14,908
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 263,917
<ACCUMULATED-NII-PRIOR> 126,877
<ACCUMULATED-GAINS-PRIOR> 658,938
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,802,863
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,107,064
<AVERAGE-NET-ASSETS> 692,610
<PER-SHARE-NAV-BEGIN> 14.06
<PER-SHARE-NII> 0.06
<PER-SHARE-GAIN-APPREC> 0.66
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 14.78
<EXPENSE-RATIO> 0.82
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 064
<NAME> Small CAP Value Equity Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 574,291,070
<INVESTMENTS-AT-VALUE> 721,952,625
<RECEIVABLES> 3,005,413
<ASSETS-OTHER> 284
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 724,958,322
<PAYABLE-FOR-SECURITIES> 5,430,443
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 18,222,684
<TOTAL-LIABILITIES> 23,653,127
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 545,984,034
<SHARES-COMMON-STOCK> 47,349,059
<SHARES-COMMON-PRIOR> 48,544,773
<ACCUMULATED-NII-CURRENT> 3,722,927
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 3,936,679
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 147,661,555
<NET-ASSETS> 700,179,637
<DIVIDEND-INCOME> 4,076,167
<INTEREST-INCOME> 1,618,707
<OTHER-INCOME> 0
<EXPENSES-NET> 2,103,047
<NET-INVESTMENT-INCOME> 3,591,827
<REALIZED-GAINS-CURRENT> 3,275,279
<APPREC-INCREASE-CURRENT> 28,423,293
<NET-CHANGE-FROM-OPS> 35,290,399
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,079,227
<NUMBER-OF-SHARES-REDEEMED> 11,274,941
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 17,601,913
<ACCUMULATED-NII-PRIOR> 126,877
<ACCUMULATED-GAINS-PRIOR> 658,938
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 1,802,863
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2,107,064
<AVERAGE-NET-ASSETS> 648,030,610
<PER-SHARE-NAV-BEGIN> 14.06
<PER-SHARE-NII> 0.08
<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> 14.79
<EXPENSE-RATIO> 0.65
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 071
<NAME> International Equity Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 769,230,747
<INVESTMENTS-AT-VALUE> 800,830,594
<RECEIVABLES> 16,996,588
<ASSETS-OTHER> 1,910,461
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 819,737,643
<PAYABLE-FOR-SECURITIES> 11,363,802
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 89,582,409
<TOTAL-LIABILITIES> 100,946,211
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 655,603,638
<SHARES-COMMON-STOCK> 11,917
<SHARES-COMMON-PRIOR> 11,834
<ACCUMULATED-NII-CURRENT> 3,016,562
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 28,625,628
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 31,545,604
<NET-ASSETS> 144,289
<DIVIDEND-INCOME> 1,207
<INTEREST-INCOME> 123
<OTHER-INCOME> 0
<EXPENSES-NET> 1,114
<NET-INVESTMENT-INCOME> 216
<REALIZED-GAINS-CURRENT> 4,628
<APPREC-INCREASE-CURRENT> 3,862
<NET-CHANGE-FROM-OPS> 8,706
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 83
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 9,706
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 5,183,290
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 2,883,632
<INTEREST-EXPENSE> 6,978
<GROSS-EXPENSE> 3,532,533
<AVERAGE-NET-ASSETS> 138,819
<PER-SHARE-NAV-BEGIN> 11.37
<PER-SHARE-NII> 0.02
<PER-SHARE-GAIN-APPREC> 0.72
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 12.11
<EXPENSE-RATIO> 1.62
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 072
<NAME> International Equity Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 769,230,747
<INVESTMENTS-AT-VALUE> 800,830,594
<RECEIVABLES> 16,996,588
<ASSETS-OTHER> 1,910,461
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 819,737,643
<PAYABLE-FOR-SECURITIES> 11,363,802
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 89,582,409
<TOTAL-LIABILITIES> 100,946,211
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 655,603,638
<SHARES-COMMON-STOCK> 8,540
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 3,016,562
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 28,625,628
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 31,545,604
<NET-ASSETS> 103,462
<DIVIDEND-INCOME> 467
<INTEREST-INCOME> 48
<OTHER-INCOME> 0
<EXPENSES-NET> 205
<NET-INVESTMENT-INCOME> 310
<REALIZED-GAINS-CURRENT> 1,030
<APPREC-INCREASE-CURRENT> (357)
<NET-CHANGE-FROM-OPS> 983
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 8,540
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 103,462
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 5,183,290
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 2,883,632
<INTEREST-EXPENSE> 6,978
<GROSS-EXPENSE> 3,532,533
<AVERAGE-NET-ASSETS> 101,951
<PER-SHARE-NAV-BEGIN> 12.00
<PER-SHARE-NII> 0.04
<PER-SHARE-GAIN-APPREC> 0.08
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 12.12
<EXPENSE-RATIO> 1.29
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 073
<NAME> International Equity Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 769,230,747
<INVESTMENTS-AT-VALUE> 800,830,594
<RECEIVABLES> 16,996,588
<ASSETS-OTHER> 1,910,461
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 819,737,643
<PAYABLE-FOR-SECURITIES> 11,363,802
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 89,582,409
<TOTAL-LIABILITIES> 100,946,211
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 655,603,638
<SHARES-COMMON-STOCK> 82,432
<SHARES-COMMON-PRIOR> 44,247
<ACCUMULATED-NII-CURRENT> 3,016,562
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 28,625,628
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 31,545,604
<NET-ASSETS> 999,879
<DIVIDEND-INCOME> 7,028
<INTEREST-INCOME> 715
<OTHER-INCOME> 0
<EXPENSES-NET> 4,150
<NET-INVESTMENT-INCOME> 3,593
<REALIZED-GAINS-CURRENT> 27,957
<APPREC-INCREASE-CURRENT> 21,010
<NET-CHANGE-FROM-OPS> 52,560
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 52,035
<NUMBER-OF-SHARES-REDEEMED> 13,850
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 496,961
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 5,183,290
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 2,883,632
<INTEREST-EXPENSE> 6,978
<GROSS-EXPENSE> 3,532,533
<AVERAGE-NET-ASSETS> 747,790
<PER-SHARE-NAV-BEGIN> 11.37
<PER-SHARE-NII> 0.06
<PER-SHARE-GAIN-APPREC> 0.70
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 12.13
<EXPENSE-RATIO> 1.12
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 074
<NAME> International Equity Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 769,230,747
<INVESTMENTS-AT-VALUE> 800,830,594
<RECEIVABLES> 16,996,588
<ASSETS-OTHER> 1,910,461
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 819,737,643
<PAYABLE-FOR-SECURITIES> 11,363,802
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 89,582,409
<TOTAL-LIABILITIES> 100,946,211
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 655,603,638
<SHARES-COMMON-STOCK> 59,129,928
<SHARES-COMMON-PRIOR> 56,352,157
<ACCUMULATED-NII-CURRENT> 3,016,562
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 28,625,628
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 31,545,604
<NET-ASSETS> 717,543,802
<DIVIDEND-INCOME> 5,941,700
<INTEREST-INCOME> 604,785
<OTHER-INCOME> 0
<EXPENSES-NET> 3,534,042
<NET-INVESTMENT-INCOME> 3,012,443
<REALIZED-GAINS-CURRENT> 23,408,723
<APPREC-INCREASE-CURRENT> 18,570,446
<NET-CHANGE-FROM-OPS> 44,991,612
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 15,980,801
<NUMBER-OF-SHARES-REDEEMED> 13,203,030
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 77,045,953
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 5,183,290
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 2,883,632
<INTEREST-EXPENSE> 6,978
<GROSS-EXPENSE> 3,532,533
<AVERAGE-NET-ASSETS> 683,140,577
<PER-SHARE-NAV-BEGIN> 11.37
<PER-SHARE-NII> 0.05
<PER-SHARE-GAIN-APPREC> 0.72
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 12.14
<EXPENSE-RATIO> 1.04
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 091
<NAME> Growth Equity Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 23,378,939
<INVESTMENTS-AT-VALUE> 25,307,870
<RECEIVABLES> 760,483
<ASSETS-OTHER> 1,072,560
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 27,140,913
<PAYABLE-FOR-SECURITIES> 448,749
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 21,942
<TOTAL-LIABILITIES> 470,691
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,030,552
<SHARES-COMMON-STOCK> 10,100
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 13,711
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (302,971)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,928,930
<NET-ASSETS> 107,539
<DIVIDEND-INCOME> 67
<INTEREST-INCOME> 98
<OTHER-INCOME> 0
<EXPENSES-NET> 207
<NET-INVESTMENT-INCOME> (42)
<REALIZED-GAINS-CURRENT> (1,223)
<APPREC-INCREASE-CURRENT> 7,804
<NET-CHANGE-FROM-OPS> 6,539
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,100
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 107,539
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 27,736
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 35,691
<AVERAGE-NET-ASSETS> 95,103
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.00
<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> 10.65
<EXPENSE-RATIO> 1.30
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 092
<NAME> Growth Equity Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 23,378,939
<INVESTMENTS-AT-VALUE> 25,307,870
<RECEIVABLES> 760,483
<ASSETS-OTHER> 1,072,560
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 27,140,913
<PAYABLE-FOR-SECURITIES> 448,749
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 21,942
<TOTAL-LIABILITIES> 470,691
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,030,552
<SHARES-COMMON-STOCK> 10,152
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 13,711
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (302,971)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,928,930
<NET-ASSETS> 108,133
<DIVIDEND-INCOME> 67
<INTEREST-INCOME> 98
<OTHER-INCOME> 0
<EXPENSES-NET> 169
<NET-INVESTMENT-INCOME> (4)
<REALIZED-GAINS-CURRENT> (1,230)
<APPREC-INCREASE-CURRENT> 7,847
<NET-CHANGE-FROM-OPS> 6,613
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,152
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 108,133
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 27,736
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 35,691
<AVERAGE-NET-ASSETS> 95,619
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.00
<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> 10.65
<EXPENSE-RATIO> 1.09
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 093
<NAME> Growth Equity Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 23,378,939
<INVESTMENTS-AT-VALUE> 25,307,870
<RECEIVABLES> 760,483
<ASSETS-OTHER> 1,072,560
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 27,140,913
<PAYABLE-FOR-SECURITIES> 448,749
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 21,942
<TOTAL-LIABILITIES> 470,691
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,030,552
<SHARES-COMMON-STOCK> 10,100
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 13,711
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (302,971)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,928,930
<NET-ASSETS> 107,604
<DIVIDEND-INCOME> 67
<INTEREST-INCOME> 98
<OTHER-INCOME> 0
<EXPENSES-NET> 145
<NET-INVESTMENT-INCOME> 20
<REALIZED-GAINS-CURRENT> (1,224)
<APPREC-INCREASE-CURRENT> 7,808
<NET-CHANGE-FROM-OPS> 6,604
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,100
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 107,604
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 27,736
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 35,691
<AVERAGE-NET-ASSETS> 95,131
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.00
<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> 10.65
<EXPENSE-RATIO> 0.94
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 094
<NAME> Growth Equity Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 23,378,939
<INVESTMENTS-AT-VALUE> 25,307,870
<RECEIVABLES> 760,483
<ASSETS-OTHER> 1,072,560
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 27,140,913
<PAYABLE-FOR-SECURITIES> 448,749
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 21,942
<TOTAL-LIABILITIES> 470,691
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,030,552
<SHARES-COMMON-STOCK> 2,472,544
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 13,711
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (302,971)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,928,930
<NET-ASSETS> 26,346,946
<DIVIDEND-INCOME> 19,824
<INTEREST-INCOME> 29,083
<OTHER-INCOME> 0
<EXPENSES-NET> 35,170
<NET-INVESTMENT-INCOME> 13,737
<REALIZED-GAINS-CURRENT> (299,294)
<APPREC-INCREASE-CURRENT> 1,905,471
<NET-CHANGE-FROM-OPS> 1,619,914
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 2,502,544
<NUMBER-OF-SHARES-REDEEMED> 30,000
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 26,346,946
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 27,736
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 35,691
<AVERAGE-NET-ASSETS> 24,947,363
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.01
<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> 10.66
<EXPENSE-RATIO> 0.87
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 101
<NAME> Mid Cap Growth Equity Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 23,747,458
<INVESTMENTS-AT-VALUE> 24,755,310
<RECEIVABLES> 756,169
<ASSETS-OTHER> 1,403,560
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 26,915,039
<PAYABLE-FOR-SECURITIES> 1,073,642
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 21,809
<TOTAL-LIABILITIES> 1,095,451
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,120
<SHARES-COMMON-STOCK> 10,100
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> (5,655)
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (186,729)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,007,852
<NET-ASSETS> 104,266
<DIVIDEND-INCOME> 39
<INTEREST-INCOME> 49
<OTHER-INCOME> 0
<EXPENSES-NET> 207
<NET-INVESTMENT-INCOME> (119)
<REALIZED-GAINS-CURRENT> (763)
<APPREC-INCREASE-CURRENT> 4,149
<NET-CHANGE-FROM-OPS> 3,267
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,100
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 104,266
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 27,946
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 35,827
<AVERAGE-NET-ASSETS> 93,009
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> (0.01)
<PER-SHARE-GAIN-APPREC> 0.33
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.32
<EXPENSE-RATIO> 1.38
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 102
<NAME> Mid Cap Growth Equity Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 23,747,458
<INVESTMENTS-AT-VALUE> 24,755,310
<RECEIVABLES> 756,169
<ASSETS-OTHER> 1,403,560
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 26,915,039
<PAYABLE-FOR-SECURITIES> 1,073,642
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 21,809
<TOTAL-LIABILITIES> 1,095,451
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,120
<SHARES-COMMON-STOCK> 10,102
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> (5,655)
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (186,729)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,007,852
<NET-ASSETS> 104,430
<DIVIDEND-INCOME> 39
<INTEREST-INCOME> 49
<OTHER-INCOME> 0
<EXPENSES-NET> 170
<NET-INVESTMENT-INCOME> (82)
<REALIZED-GAINS-CURRENT> (764)
<APPREC-INCREASE-CURRENT> 4,156
<NET-CHANGE-FROM-OPS> 3,310
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,102
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 104,430
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 27,946
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 35,827
<AVERAGE-NET-ASSETS> 93,139
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> (0.01)
<PER-SHARE-GAIN-APPREC> 0.35
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.34
<EXPENSE-RATIO> 1.13
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 103
<NAME> Mid Cap Growth Equity Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 23,747,458
<INVESTMENTS-AT-VALUE> 24,755,310
<RECEIVABLES> 756,169
<ASSETS-OTHER> 1,403,560
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 26,915,039
<PAYABLE-FOR-SECURITIES> 1,073,642
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 21,809
<TOTAL-LIABILITIES> 1,095,451
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,120
<SHARES-COMMON-STOCK> 10,100
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> (5,655)
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (186,729)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,007,852
<NET-ASSETS> 104,328
<DIVIDEND-INCOME> 39
<INTEREST-INCOME> 49
<OTHER-INCOME> 0
<EXPENSES-NET> 147
<NET-INVESTMENT-INCOME> (59)
<REALIZED-GAINS-CURRENT> (763)
<APPREC-INCREASE-CURRENT> 4,151
<NET-CHANGE-FROM-OPS> 3,329
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,100
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 104,328
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 27,946
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 35,827
<AVERAGE-NET-ASSETS> 93,036
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> (0.01)
<PER-SHARE-GAIN-APPREC> 0.34
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.33
<EXPENSE-RATIO> 0.98
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 104
<NAME> Mid Cap Growth Equity Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 23,747,458
<INVESTMENTS-AT-VALUE> 24,755,310
<RECEIVABLES> 756,169
<ASSETS-OTHER> 1,403,560
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 26,915,039
<PAYABLE-FOR-SECURITIES> 1,073,642
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 21,809
<TOTAL-LIABILITIES> 1,095,451
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,120
<SHARES-COMMON-STOCK> 2,470,100
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> (5,655)
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (186,729)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 1,007,852
<NET-ASSETS> 25,506,564
<DIVIDEND-INCOME> 13,189
<INTEREST-INCOME> 16,719
<OTHER-INCOME> 0
<EXPENSES-NET> 35,303
<NET-INVESTMENT-INCOME> (5,395)
<REALIZED-GAINS-CURRENT> (184,439)
<APPREC-INCREASE-CURRENT> 995,396
<NET-CHANGE-FROM-OPS> 805,562
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 2,500,100
<NUMBER-OF-SHARES-REDEEMED> 30,000
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 25,506,564
<ACCUMULATED-NII-PRIOR> 104,328
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 27,946
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 35,827
<AVERAGE-NET-ASSETS> 24,418,957
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.00
<PER-SHARE-GAIN-APPREC> 0.33
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.33
<EXPENSE-RATIO> 0.89
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 111
<NAME> Small Cap Growth Equity Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 19,434,932
<INVESTMENTS-AT-VALUE> 21,546,366
<RECEIVABLES> 395,595
<ASSETS-OTHER> 5,963,628
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 27,905,589
<PAYABLE-FOR-SECURITIES> 557,961
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 26,140
<TOTAL-LIABILITIES> 584,101
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,340
<SHARES-COMMON-STOCK> 10,160
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 24,545
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 181,169
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 2,111,434
<NET-ASSETS> 110,937
<DIVIDEND-INCOME> 43
<INTEREST-INCOME> 206
<OTHER-INCOME> 0
<EXPENSES-NET> 250
<NET-INVESTMENT-INCOME> (1)
<REALIZED-GAINS-CURRENT> 736
<APPREC-INCREASE-CURRENT> 9,201
<NET-CHANGE-FROM-OPS> 9,936
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,160
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 110,937
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 33,774
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 43,039
<AVERAGE-NET-ASSETS> 96,701
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.00
<PER-SHARE-GAIN-APPREC> 0.92
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.92
<EXPENSE-RATIO> 1.60
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 112
<NAME> Small Cap Growth Equity Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 19,434,932
<INVESTMENTS-AT-VALUE> 21,546,366
<RECEIVABLES> 395,595
<ASSETS-OTHER> 5,963,628
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 27,905,589
<PAYABLE-FOR-SECURITIES> 557,961
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 26,140
<TOTAL-LIABILITIES> 584,101
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,340
<SHARES-COMMON-STOCK> 10,195
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 24,545
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 181,169
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 2,111,434
<NET-ASSETS> 111,351
<DIVIDEND-INCOME> 43
<INTEREST-INCOME> 206
<OTHER-INCOME> 0
<EXPENSES-NET> 211
<NET-INVESTMENT-INCOME> 38
<REALIZED-GAINS-CURRENT> 739
<APPREC-INCREASE-CURRENT> 9,233
<NET-CHANGE-FROM-OPS> 10,010
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,195
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 111,351
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 33,774
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 43,039
<AVERAGE-NET-ASSETS> 97,048
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.00
<PER-SHARE-GAIN-APPREC> 0.92
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.92
<EXPENSE-RATIO> 1.35
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 113
<NAME> Small Cap Growth Equity Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 19,434,932
<INVESTMENTS-AT-VALUE> 21,546,366
<RECEIVABLES> 395,595
<ASSETS-OTHER> 5,963,628
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 27,905,589
<PAYABLE-FOR-SECURITIES> 557,961
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 26,140
<TOTAL-LIABILITIES> 584,101
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,340
<SHARES-COMMON-STOCK> 10,160
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 24,545
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 181,169
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 2,111,434
<NET-ASSETS> 111,004
<DIVIDEND-INCOME> 44
<INTEREST-INCOME> 207
<OTHER-INCOME> 0
<EXPENSES-NET> 187
<NET-INVESTMENT-INCOME> 64
<REALIZED-GAINS-CURRENT> 736
<APPREC-INCREASE-CURRENT> 9,205
<NET-CHANGE-FROM-OPS> 10,005
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,160
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 111,004
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 33,774
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 43,039
<AVERAGE-NET-ASSETS> 96,729
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.01
<PER-SHARE-GAIN-APPREC> 0.92
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.93
<EXPENSE-RATIO> 1.20
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 114
<NAME> Small Cap Growth Equity Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 19,434,932
<INVESTMENTS-AT-VALUE> 21,546,366
<RECEIVABLES> 395,595
<ASSETS-OTHER> 5,963,628
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 27,905,589
<PAYABLE-FOR-SECURITIES> 557,961
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 26,140
<TOTAL-LIABILITIES> 584,101
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,340
<SHARES-COMMON-STOCK> 2,469,919
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 24,545
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 181,169
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 2,111,434
<NET-ASSETS> 26,988,196
<DIVIDEND-INCOME> 11,623
<INTEREST-INCOME> 55,212
<OTHER-INCOME> 0
<EXPENSES-NET> 42,391
<NET-INVESTMENT-INCOME> 24,444
<REALIZED-GAINS-CURRENT> 178,958
<APPREC-INCREASE-CURRENT> 2,083,795
<NET-CHANGE-FROM-OPS> 2,287,197
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 2,500,100
<NUMBER-OF-SHARES-REDEEMED> 30,181
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 26,988,196
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 33,774
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 43,039
<AVERAGE-NET-ASSETS> 25,190,274
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.01
<PER-SHARE-GAIN-APPREC> 0.92
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 10.93
<EXPENSE-RATIO> 1.04
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 121
<NAME> Diversified Bond Fund, Class A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 24,939,008
<INVESTMENTS-AT-VALUE> 24,519,120
<RECEIVABLES> 226,211
<ASSETS-OTHER> 3,784
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 24,749,115
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 18,244
<TOTAL-LIABILITIES> 18,244
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,000
<SHARES-COMMON-STOCK> 10,100
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 236,202
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (89,443)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (419,888)
<NET-ASSETS> 99,828
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 1,026
<OTHER-INCOME> 0
<EXPENSES-NET> 179
<NET-INVESTMENT-INCOME> 847
<REALIZED-GAINS-CURRENT> (361)
<APPREC-INCREASE-CURRENT> (1,657)
<NET-CHANGE-FROM-OPS> (1,171)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,100
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 99,828
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 20,011
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 29,321
<AVERAGE-NET-ASSETS> 93,201
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.08
<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> 9.88
<EXPENSE-RATIO> 1.19
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 122
<NAME> Diversified Bond Fund, Class L
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 24,939,008
<INVESTMENTS-AT-VALUE> 24,519,120
<RECEIVABLES> 226,211
<ASSETS-OTHER> 3,784
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 24,749,115
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 18,244
<TOTAL-LIABILITIES> 18,244
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,000
<SHARES-COMMON-STOCK> 10,100
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 236,202
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (89,443)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (419,888)
<NET-ASSETS> 99,866
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 1,026
<OTHER-INCOME> 0
<EXPENSES-NET> 142
<NET-INVESTMENT-INCOME> 884
<REALIZED-GAINS-CURRENT> (361)
<APPREC-INCREASE-CURRENT> (1,657)
<NET-CHANGE-FROM-OPS> (1,134)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,100
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 99,866
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 20,011
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 29,321
<AVERAGE-NET-ASSETS> 93,217
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.09
<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> 9.89
<EXPENSE-RATIO> 0.94
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 123
<NAME> Diversified Bond Fund, Class Y
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 24,939,008
<INVESTMENTS-AT-VALUE> 24,519,120
<RECEIVABLES> 226,211
<ASSETS-OTHER> 3,784
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 24,749,115
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 18,244
<TOTAL-LIABILITIES> 18,244
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,000
<SHARES-COMMON-STOCK> 10,100
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 236,202
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (89,443)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (419,888)
<NET-ASSETS> 99,888
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 1,026
<OTHER-INCOME> 0
<EXPENSES-NET> 119
<NET-INVESTMENT-INCOME> 907
<REALIZED-GAINS-CURRENT> (361)
<APPREC-INCREASE-CURRENT> (1,658)
<NET-CHANGE-FROM-OPS> (1,112)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 10,100
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 99,888
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 20,011
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 29,321
<AVERAGE-NET-ASSETS> 93,228
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.09
<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> 9.89
<EXPENSE-RATIO> 0.79
</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, 1999
and is qualified in its entirety by reference to
such financial statements.
</LEGEND>
<SERIES>
<NUMBER> 124
<NAME> Diversified Bond Fund, Class S
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-1999
<INVESTMENTS-AT-COST> 24,939,008
<INVESTMENTS-AT-VALUE> 24,519,120
<RECEIVABLES> 226,211
<ASSETS-OTHER> 3,784
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 24,749,115
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 18,244
<TOTAL-LIABILITIES> 18,244
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 25,004,000
<SHARES-COMMON-STOCK> 2,470,100
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 236,202
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (89,443)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (419,888)
<NET-ASSETS> 24,431,289
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 262,445
<OTHER-INCOME> 0
<EXPENSES-NET> 28,881
<NET-INVESTMENT-INCOME> 233,564
<REALIZED-GAINS-CURRENT> (88,360)
<APPREC-INCREASE-CURRENT> (414,916)
<NET-CHANGE-FROM-OPS> (269,712)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 2,500,100
<NUMBER-OF-SHARES-REDEEMED> 30,000
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 24,431,289
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 20,011
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 29,321
<AVERAGE-NET-ASSETS> 24,479,551
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0.09
<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> 9.89
<EXPENSE-RATIO> 0.73
</TABLE>
EXHIBIT INDEX TO FORM N-SAR
OF MASSMUTUAL INSTITUTIONAL FUNDS
FOR THE PERIOD ENDED JUNE 30, 1999
Exhibit No. Description
77C Submission of matters to a vote of security holders
77I Terms of new or amended securities
77J Revaluation of assets or restatement of capital share account
77Q(1)(e) Investment Management Agreement dated May 3, 1999 between
Massachusetts Mutual Life Insurance Company and MassMutual
Institutional Funds on behalf of MassMutual Core Bond Fund,
MassMutual Small Cap Value Equity Fund, MassMutual Diversified
Bond Fund, MassMutual Core Equity Fund, MassMutual Growth Equity
Fund, MassMutual Mid Cap Growth Equity Fund, MassMutual Small Cap
Growth Equity Fund, and MassMutual Balanced Fund.
Investment Sub-Advisory Agreement effective as of May 3, 1999,
between Massachusetts Mutual Life Insurance Company and
Massachusetts Financial Services Company.
Investment Sub-Advisory Agreement effective as of May 3, 1999,
between Massachusetts Mutual Life Insurance Company and
Miller Anderson & Sherrerd, LLP.
Investment Sub-Advisory Agreement effective as of May 3, 1999,
between Massachusetts Mutual Life Insurance Company and
J.P. Morgan Investment Management Inc.
Investment Sub-Advisory Agreement effective as of May 3, 1999,
between Massachusetts Mutual Life Insurance Company and
Waddell & Reed Investment Management Company.
For Period Ended 06/30/99
File No. 811-8274
77C Submission of matters to a vote of security holders
On or about April 2, 1999, the Funds distributed an information statement
disclosing action taken by written consent of the majority
shareholders of each of the following Funds: MassMutual Prime Fund,
MassMutual Short-Term Bond Fund, MassMutual Core Bond Fund,
MassMutual Balanced Fund, MassMutual Core Equity Fund,
MassMutual Small Cap Value Equity Fund, MassMutual Indexed Equity Fund and
MassMutual International Equity Fund. Massachusetts Mutual Life
Insurance Company ("MassMutual") was the majority shareholder of
these Funds as of February 1, 1999, the record date set by the Board
of Trustees of the Funds. (The record date is the date for
determining the number of shares and the shareholders of each Fund entitled
to give consent and to receive the information
statement.) On the record date, MassMutual owned the following percentages
of each of the Funds:
Percentage of Fund's Shares
Name of Fund Owned by MassMutual
Prime Fund 92.67%
Short-Term Bond Fund 100.00%
Core Bond Fund 99.94%
Balanced Fund 94.47%
Core Equity Fund 99.98%
Small Cap Value Fund 99.94%
Indexed Equity Fund 99.83%
International Equity Fund 99.95%
The Trustees approved the following proposals on February 1, 1999:
1. New Investment Management Agreements reflecting increased
investment advisory fees paid to MassMutual, as Investment
Manager, for the following Funds: Core Bond Fund, Core Equity
Fund, Small Cap Value Fund and Balanced Fund. MassMutual, as
investment adviser, will be paid at an annual rate of the average
daily net assets of each Fund, as follows: .48% for Core Bond Fund
and Balanced Fund (up from .45%), .50% for Core Equity Fund (up
from .45%); .58% for the Small Cap Value Fund (up from .55%).
2. Amendment to each Administrative and Shareholder Services
Agreement for the Prime Fund, Short-Term Bond Fund, Core Bond
Fund, Balanced Fund, Core Equity Fund, Small Cap Value Fund,
Indexed Equity Fund and International Equity Fund to (i) delete
the requirement that Trustees of the relevant Fund approve any
amendments thereto, and (ii) delete the provision terminating the
agreement upon its assignment.
MassMutual, as majority shareholder, approved both proposals by written consent,
effective May 3, 1999.
For Period Ended 06/30/99
File No. 811-8274
77I Terms of new or amended securities
Effective May 3, 1999, Registrant began to issue a new class of shares, known
as the Class L shares. Class L shares may be purchased
by: (1) non-qualified deferred compensation plans; (2) qualified plans under
Code Section 401(a), Code Section 403(b) plans, Code
Section 457 plans, and other retirement plans where plan assets of the employer
generally or are expected to exceed $1 million; and
(3)other institutional investors with assets generally in excess of $1 million.
These Eligible Purchasers must have an agreement with Massachusetts Mutual Life
Insurance Company or one of its affiliates to
purchase Class L shares. Class L Shares are generally sold in connection with
the use of an intermediary performing third party
administration and/or other shareholder services.
Class L shares of each Fund are purchased directly from Registrant without a
front-end sales charge. Therefore, 100% of an
investor's money is invested in the Fund or Funds of its choice, Class L
shares do not have deferred sales charges or any Rule 12b-1
distribution or service fees.
For Period Ended 06/30/99
File No. 811-8274
77J Revaluation of assets or restatement of capital share account
Registrant's Board of Trustees approved Valuation Guidelines for Illiquid
Securities for the MassMutual Diversified Bond Fund, a fund
which may hold private debt securities. The private debt securities held
by the MassMutual Diversified Bond Fund shall be valued
using a discounted cash flow methodology. The price of a private debt
security shall be equal to the present value of the expected
future cash flows, discounted at the required yield. The "required yield"
is made up of two components, (1) the current yield for a
Treasury security with similar average life, and (2) a spread which reflects
issue-specific characteristics. Derivatives are also
covered by this policy.
Additionally Registrant's investment valuation procedures were amended so that
portfolio securities with a remaining maturity of 60
or more but less than 367 days will be valued using a discount yield from an
independent broker, which approximates current value.
For Period Ended 06/30/99
File No. 811-8274
77Q(1)(e) Investment Management Agreement dated May 3, 1999 between
Massachusetts Mutual Life Insurance Company and MassMutual
Institutional Funds on behalf of MassMutual Core Bond Fund,
MassMutual Small Cap Value Equity Fund, MassMutual Diversified Bond
Fund, MassMutual Core Equity Fund, MassMutual Growth Equity Fund,
MassMutual Mid Cap Growth Equity Fund, MassMutual Small Cap Growth
Equity Fund, and MassMutual Balanced Fund was filed as Exhibit No.
D(1) to Post-Effective Amendment No. 11 to Registrant's
Registration Statement on Form N-1A (as filed with the Securities
and Exchange Commission ("SEC") via EDGAR), and is incorporated
herein by reference.
Investment Sub-Advisory Agreement effective as of May 3, 1999,
between Massachusetts Mutual Life Insurance Company and
Massachusetts Financial Services Company regarding MassMutual
Growth Equity Fund was filed as Exhibit No. D(5) to Post-Effective
Amendment No. 11 to Registrant's Registration Statement on Form
N-1A (as filed with the SEC via EDGAR), and is incorporated herein
by reference.
Investment Sub-Advisory Agreement effective as of May 3, 1999,
between Massachusetts Mutual Life Insurance Company and
Miller Anderson & Sherrerd, LLP regarding MassMutual Mid Cap
Growth Equity Fund was filed as Exhibit No. D(6) to Post-Effective
Amendment No. 11 to Registrant's Registration Statement on Form
N-1A (as filed with the SEC via EDGAR), and is incorporated herein
by reference.
Investment Sub-Advisory Agreement effective as of May 3, 1999,
between Massachusetts Mutual Life Insurance Company and
J.P. Morgan Investment Management Inc. regarding MassMutual Small
Cap Growth Equity Fund was filed as Exhibit No. D(7) to Post-
Effective Amendment No. 11 to Registrant's Registration Statement
on Form N-1A (as filed with the SEC via EDGAR), and is
incorporated herein by reference.
Investment Sub-Advisory Agreement effective as of May 3, 1999,
between Massachusetts Mutual Life Insurance Company and Waddell &
Reed Investment Management Company regarding MassMutual Small Cap
Growth Equity Fund was filed as Exhibit No. D(8) to Post-Effective
Amendment No. 11 to Registrant's Registration Statement on Form
N-1A (as filed with the SEC via EDGAR), and is incorporated herein
by reference.
