<PAGE> PAGE 1
000 B000000 12/31/96
000 C000000 315783
000 D000000 N
000 E000000 NF
000 F000000 Y
000 G000000 N
000 H000000 N
000 I000000 3.0
000 J000000 U
001 A000000 DREYFUS INSTITUTIONAL MONEY MARKET FUND
001 B000000 811-3025
001 C000000 2129226807
002 A000000 144 GLENN CURTISS BOULEVARD
002 B000000 UNIONDALE
002 C000000 NY
002 D010000 11556
002 D020000 0144
003 000000 N
004 000000 N
005 000000 N
006 000000 N
007 A000000 Y
007 B000000 2
007 C010100 1
007 C020100 MONEY MARKET SERIES
007 C030100 N
007 C010200 2
007 C020200 GOVERNMENT SECURITIES SERIES
007 C030200 N
007 C010300 3
007 C010400 4
007 C010500 5
007 C010600 6
007 C010700 7
007 C010800 8
007 C010900 9
007 C011000 10
015 A00AA01 THE BANK OF NEW YORK
015 B00AA01 C
015 C01AA01 NEW YORK
015 C02AA01 NY
015 C03AA01 10286
015 E01AA01 X
018 00AA00 Y
019 A00AA00 Y
019 B00AA00 152
019 C00AA00 DREYFUSFAM
022 A000001 AUBREY G. LANSTON & CO. INC.
022 B000001 13-5552129
022 C000001 6687575
022 D000001 0
<PAGE> PAGE 2
022 A000002 SBC CAPITAL MARKETS, INC.
022 B000002 13-3498485
022 C000002 5268955
022 D000002 0
022 A000003 UBS SECURITIES INC.
022 B000003 13-2932996
022 C000003 4271196
022 D000003 52311
022 A000004 DAIWA SECURITIES AMERICA INC.
022 B000004 13-5680329
022 C000004 2416000
022 D000004 0
022 A000005 NIKKO SECURITIES CO. INTERNATIONAL, INC.
022 B000005 94-1302123
022 C000005 2231742
022 D000005 0
022 A000006 LEHMAN BROTHERS INC.
022 B000006 13-2518466
022 C000006 1635777
022 D000006 155998
022 A000007 REPUBLIC NATIONAL BANK OF NEW YORK
022 B000007 13-2774727
022 C000007 1443293
022 D000007 0
022 A000008 GOLDMAN, SACHS & CO.
022 B000008 13-5108880
022 C000008 1411404
022 D000008 14723
022 A000009 SANWA SECURITIES (USA) CO., L.P.
022 B000009 13-3046258
022 C000009 1411472
022 D000009 9487
022 A000010 MORGAN STANLEY & CO. INCORPORATED
022 B000010 13-2655998
022 C000010 1348448
022 D000010 0
023 C000000 32935742
023 D000000 505725
024 00AA00 Y
077 A000000 Y
077 B000000 Y
077 C000000 N
077 D000000 N
077 E000000 N
077 F000000 N
077 G000000 N
077 H000000 N
077 I000000 N
077 J000000 N
077 K000000 N
077 L000000 N
<PAGE> PAGE 3
077 M000000 N
077 N000000 N
077 O000000 N
077 P000000 N
077 Q010000 N
077 Q020000 N
077 Q030000 N
080 A00AA00 VIGILANT INSURANCE COMPANY
080 B00AA00 NATIONAL UNION FIRE INSURANCE CO OF PITTS PA
080 C00AA00 125000
081 A00AA00 Y
081 B00AA00 168
082 A00AA00 N
082 B00AA00 0
083 A00AA00 N
083 B00AA00 0
084 A00AA00 N
084 B00AA00 0
085 A00AA00 Y
085 B00AA00 N
025 A000101 GOLDMAN, SACHS & CO.
025 B000101 13-5108880
025 C000101 D
025 D000101 19376
025 A000102 LEHMAN BROTHERS INC.
025 B000102 13-2518466
025 C000102 D
025 D000102 19712
025 A000103 AUBREY G. LANSTON & CO. INC.
025 B000103 13-5552129
025 C000103 D
025 D000103 36000
028 A010100 484885
028 A020100 201
028 A030100 0
028 A040100 429831
028 B010100 465161
028 B020100 208
028 B030100 0
028 B040100 448355
028 C010100 477088
028 C020100 202
028 C030100 0
028 C040100 445495
028 D010100 287462
028 D020100 212
028 D030100 0
028 D040100 359267
028 E010100 387455
028 E020100 198
028 E030100 0
<PAGE> PAGE 4
028 E040100 338424
028 F010100 425084
028 F020100 281
028 F030100 0
028 F040100 405202
028 G010100 2527135
028 G020100 1302
028 G030100 0
028 G040100 2426574
028 H000100 0
055 A000100 Y
055 B000100 N
056 000100 N
057 000100 N
062 A000100 Y
062 B000100 0.0
062 C000100 24.4
062 D000100 9.1
062 E000100 0.0
062 F000100 8.7
062 G000100 0.0
062 H000100 0.0
062 I000100 34.5
062 J000100 4.1
062 K000100 0.0
062 L000100 18.4
062 M000100 0.0
062 N000100 0.0
062 O000100 0.0
062 P000100 0.0
062 Q000100 0.0
062 R000100 0.0
063 A000100 67
063 B000100 0.0
064 A000100 Y
064 B000100 N
071 A000100 0
071 B000100 0
071 C000100 0
071 D000100 0
072 A000100 12
072 B000100 24257
072 C000100 0
072 D000100 0
072 E000100 0
072 F000100 2208
072 G000100 0
072 H000100 0
072 I000100 157
072 J000100 87
072 K000100 0
<PAGE> PAGE 5
072 L000100 8
072 M000100 54
072 N000100 17
072 O000100 1
072 P000100 0
072 Q000100 0
072 R000100 18
072 S000100 5
072 T000100 0
072 U000100 0
072 V000100 0
072 W000100 5
072 X000100 2560
072 Y000100 0
072 Z000100 21697
072AA000100 81
072BB000100 1
072CC010100 0
072CC020100 0
072DD010100 21697
072DD020100 0
072EE000100 0
073 A010100 0.0491
073 A020100 0.0000
073 B000100 0.0000
073 C000100 0.0000
074 A000100 1321
074 B000100 44174
074 C000100 435281
074 D000100 0
074 E000100 0
074 F000100 0
074 G000100 0
074 H000100 0
074 I000100 0
074 J000100 0
074 K000100 0
074 L000100 2641
074 M000100 14
074 N000100 483431
074 O000100 0
074 P000100 200
074 Q000100 0
074 R010100 0
074 R020100 0
074 R030100 0
074 R040100 75
074 S000100 0
074 T000100 483156
074 U010100 483167
074 U020100 0
<PAGE> PAGE 6
074 V010100 1.00
074 V020100 0.00
074 W000100 0.9992
074 X000100 3630
074 Y000100 0
075 A000100 441620
075 B000100 0
076 000100 0.00
025 A000201 AUBREY G. LANSTON & CO. INC.
025 B000201 13-5552129
025 C000201 D
025 D000201 5000
025 A000202 DAIWA SECURITIES AMERICA INC.
025 B000202 13-5680329
025 C000202 D
025 D000202 7000
025 A000203 THE NIKKO SECURITIES CO. INTERNATIONAL INC.
025 B000203 94-1302123
025 C000203 D
025 D000203 6000
025 A000204 UBS SECURITIES INC.
025 B000204 13-2932996
025 C000204 D
025 D000204 10000
028 A010200 39084
028 A020200 157
028 A030200 0
028 A040200 55088
028 B010200 25849
028 B020200 161
028 B030200 0
028 B040200 30035
028 C010200 38276
028 C020200 161
028 C030200 0
028 C040200 40071
028 D010200 42311
028 D020200 115
028 D030200 0
028 D040200 52881
028 E010200 29796
028 E020200 112
028 E030200 0
028 E040200 36178
028 F010200 31567
028 F020200 146
028 F030200 0
028 F040200 45540
028 G010200 206883
028 G020200 852
028 G030200 0
<PAGE> PAGE 7
028 G040200 259793
028 H000200 0
055 A000200 Y
055 B000200 N
056 000200 N
057 000200 N
062 A000200 Y
062 B000200 58.1
062 C000200 0.0
062 D000200 41.1
062 E000200 0.0
062 F000200 0.0
062 G000200 0.0
062 H000200 0.0
062 I000200 0.0
062 J000200 0.0
062 K000200 0.0
062 L000200 0.0
062 M000200 0.0
062 N000200 0.0
062 O000200 0.0
062 P000200 0.0
062 Q000200 0.0
062 R000200 0.0
063 A000200 79
063 B000200 0.0
064 A000200 Y
064 B000200 N
071 A000200 0
071 B000200 0
071 C000200 0
071 D000200 0
072 A000200 12
072 B000200 8169
072 C000200 0
072 D000200 0
072 E000200 0
072 F000200 762
072 G000200 0
072 H000200 0
072 I000200 67
072 J000200 68
072 K000200 0
072 L000200 0
072 M000200 19
072 N000200 19
072 O000200 1
072 P000200 0
072 Q000200 0
072 R000200 12
072 S000200 2
<PAGE> PAGE 8
072 T000200 0
072 U000200 0
072 V000200 0
072 W000200 4
072 X000200 954
072 Y000200 0
072 Z000200 7215
072AA000200 22
072BB000200 1
072CC010200 0
072CC020200 0
072DD010200 7215
072DD020200 0
072EE000200 0
073 A010200 0.0473
073 A020200 0.0000
073 B000200 0.0000
073 C000200 0.0000
074 A000200 234
074 B000200 42215
074 C000200 59647
074 D000200 0
074 E000200 0
074 F000200 0
074 G000200 0
074 H000200 0
074 I000200 0
074 J000200 0
074 K000200 0
074 L000200 729
074 M000200 12
074 N000200 102837
074 O000200 0
074 P000200 51
074 Q000200 0
074 R010200 0
074 R020200 0
074 R030200 0
074 R040200 60
074 S000200 0
074 T000200 102726
074 U010200 102786
074 U020200 0
074 V010200 1.00
074 V020200 0.00
074 W000200 0.9997
074 X000200 276
074 Y000200 0
075 A000200 152341
075 B000200 0
076 000200 0.00
<PAGE> PAGE 9
SIGNATURE DOUGLAS C. CONROY
TITLE ASSISTANT TREASURER
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000315783
<NAME> DREYFUS INSTITUTIONAL MONEY MARKET FUND
<SERIES>
<NUMBER> 01
<NAME> MONEY MARKET SERIES
<MULTIPLIER> 1000
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> DEC-31-1996
<PERIOD-END> DEC-31-1996
<INVESTMENTS-AT-COST> 479455
<INVESTMENTS-AT-VALUE> 479455
<RECEIVABLES> 2641
<ASSETS-OTHER> 1335
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 483431
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 275
<TOTAL-LIABILITIES> 275
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 483167
<SHARES-COMMON-STOCK> 483167
<SHARES-COMMON-PRIOR> 402124
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (11)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 483156
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 24257
<OTHER-INCOME> 0
<EXPENSES-NET> 2560
<NET-INVESTMENT-INCOME> 21697
<REALIZED-GAINS-CURRENT> 80
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 21777
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (21697)
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 5173787
<NUMBER-OF-SHARES-REDEEMED> (5095326)
<SHARES-REINVESTED> 25863
<NET-CHANGE-IN-ASSETS> 81123
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (92)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 2208
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 2560
<AVERAGE-NET-ASSETS> 441620
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> .049
<PER-SHARE-GAIN-APPREC> 0
<PER-SHARE-DIVIDEND> (.049)
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> .006
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000315783
<NAME> DREYFUS INSTITUTIONAL MONEY MARKET FUND
<SERIES>
<NUMBER> 02
<NAME> GOVERNMENT SECURITIES SERIES
<MULTIPLIER> 1000
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> DEC-31-1996
<PERIOD-END> DEC-31-1996
<INVESTMENTS-AT-COST> 101862
<INVESTMENTS-AT-VALUE> 101862
<RECEIVABLES> 729
<ASSETS-OTHER> 246
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 102837
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 111
<TOTAL-LIABILITIES> 111
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 102786
<SHARES-COMMON-STOCK> 102786
<SHARES-COMMON-PRIOR> 123253
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> (60)
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 102726
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 8169
<OTHER-INCOME> 0
<EXPENSES-NET> 954
<NET-INVESTMENT-INCOME> 7215
<REALIZED-GAINS-CURRENT> 21
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 7236
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (7215)
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 574693
<NUMBER-OF-SHARES-REDEEMED> (597059)
<SHARES-REINVESTED> 1900
<NET-CHANGE-IN-ASSETS> (20446)
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> (82)
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 762
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 954
<AVERAGE-NET-ASSETS> 152341
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> .047
<PER-SHARE-GAIN-APPREC> 0
<PER-SHARE-DIVIDEND> (.047)
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> .006
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>