<PAGE> PAGE 1
000 A000000 06/30/98
000 C000000 0000812195
000 D000000 N
000 E000000 NF
000 F000000 Y
000 G000000 N
000 H000000 N
000 I000000 3.0
000 J000000 A
001 A000000 PIONEER MONEY MARKET TRUST
001 B000000 811-5099
001 C000000 6177427825
002 A000000 60 STATE STREET
002 B000000 BOSTON
002 C000000 MA
002 D010000 02109
002 D020000 1820
003 000000 N
004 000000 N
005 000000 N
006 000000 N
007 A000000 Y
007 B000000 1
007 C010100 1
007 C020100 PIONEER CASH RESERVES FUND
007 C030100 N
007 C010200 2
007 C010300 3
007 C010400 4
007 C010500 5
007 C010600 6
007 C010700 7
007 C010800 8
007 C010900 9
007 C011000 10
008 A00AA01 PIONEERING MANAGEMENT CORPORATION
008 B00AA01 A
008 C00AA01 801-8255
008 D01AA01 BOSTON
008 D02AA01 MA
008 D03AA01 02109
008 D04AA01 1820
011 A00AA01 PIONEER FUNDS DISTRIBUTOR, INC.
011 B00AA01 8-41256
011 C01AA01 BOSTON
011 C02AA01 MA
011 C03AA01 02109
011 C04AA01 1820
012 A00AA01 PIONEERING SERVICES CORPORATION
012 B00AA01 84-1359
012 C01AA01 BOSTON
<PAGE> PAGE 2
012 C02AA01 MA
012 C03AA01 02109
012 C04AA01 1820
013 A00AA01 ARTHUR ANDERSEN LLP
013 B01AA01 BOSTON
013 B02AA01 MA
013 B03AA01 02110
013 B04AA01 2812
018 00AA00 Y
019 A00AA00 Y
019 B00AA00 34
019 C00AA00 PIONEERFDS
020 C000001 0
020 C000002 0
020 C000003 0
020 C000004 0
020 C000005 0
020 C000006 0
020 C000007 0
020 C000008 0
020 C000009 0
020 C000010 0
021 000000 0
022 A000001 BROWN BROTHERS
022 B000001 13-4973745
022 C000001 1011256
022 D000001 0
022 A000002 HOUSEHOLD FINANCE
022 B000002 36-1239445
022 C000002 211127
022 D000002 0
022 A000003 LUMMIS & COMPANY
022 B000003 06-0909285
022 C000003 176184
022 D000003 0
022 A000004 AMERICAN EXPRESS CREDIT
022 B000004 11-1988350
022 C000004 110300
022 D000004 0
022 A000005 EXXON CREDIT CORP
022 B000005 13-3072652
022 C000005 109726
022 D000005 0
022 A000006 WILLIAMS CAPITAL
022 B000006 23-2177819
022 C000006 103515
022 D000006 0
022 A000007 FIRST CHICAGO CORP
022 C000007 70017
022 D000007 0
022 A000008 LANSTON, AUBREY G.
<PAGE> PAGE 3
022 B000008 13-5552129
022 C000008 67000
022 D000008 0
022 A000009 GOLDMAN SACHS
022 B000009 13-5108880
022 C000009 64846
022 D000009 0
022 A000010 TEXACO
022 B000010 74-1383447
022 C000010 50707
022 D000010 0
023 C000000 2324193
023 D000000 0
024 00AA00 N
025 D00AA01 0
025 D00AA02 0
025 D00AA03 0
025 D00AA04 0
025 D00AA05 0
025 D00AA06 0
025 D00AA07 0
025 D00AA08 0
026 A000000 N
026 B000000 N
026 C000000 N
026 D000000 Y
026 E000000 N
026 F000000 N
026 G010000 N
026 G020000 N
026 H000000 N
027 000000 Y
029 00AA00 N
030 A00AA00 0
030 B00AA00 0.00
030 C00AA00 0.00
031 A00AA00 0
031 B00AA00 0
032 00AA00 0
033 00AA00 0
045 00AA00 Y
046 00AA00 N
047 00AA00 Y
048 00AA00 0.400
048 A01AA00 0
048 A02AA00 0.000
048 B01AA00 0
048 B02AA00 0.000
048 C01AA00 0
048 C02AA00 0.000
048 D01AA00 0
<PAGE> PAGE 4
048 D02AA00 0.000
048 E01AA00 0
048 E02AA00 0.000
048 F01AA00 0
048 F02AA00 0.000
048 G01AA00 0
048 G02AA00 0.000
048 H01AA00 0
048 H02AA00 0.000
048 I01AA00 0
048 I02AA00 0.000
048 J01AA00 0
048 J02AA00 0.000
048 K01AA00 0
048 K02AA00 0.000
054 A00AA00 Y
054 B00AA00 N
054 C00AA00 N
054 D00AA00 N
054 E00AA00 N
054 F00AA00 N
054 G00AA00 N
054 H00AA00 Y
054 I00AA00 N
054 J00AA00 Y
054 K00AA00 N
054 L00AA00 N
054 M00AA00 Y
054 N00AA00 N
054 O00AA00 N
058 A00AA00 N
059 00AA00 Y
060 A00AA00 Y
060 B00AA00 Y
061 00AA00 1000
077 A000000 N
078 000000 N
080 A00AA00 ICI MUTUAL INSURANCE COMPANY
080 B00AA00 NONE
080 C00AA00 25000
081 A00AA00 Y
081 B00AA00 34
082 A00AA00 N
082 B00AA00 0
083 A00AA00 N
083 B00AA00 0
084 A00AA00 N
084 B00AA00 0
085 A00AA00 Y
085 B00AA00 N
086 A010000 0
<PAGE> PAGE 5
086 A020000 0
086 B010000 0
086 B020000 0
086 C010000 0
086 C020000 0
086 D010000 0
086 D020000 0
086 E010000 0
086 E020000 0
086 F010000 0
086 F020000 0
015 A000101 BROWN BROTHERS HARRIMAN
015 B000101 C
015 C010101 BOSTON
015 C020101 MA
015 C030101 02109
015 C040101 1975
015 E010101 X
028 A010100 73242
028 A020100 831
028 A030100 0
028 A040100 88092
028 B010100 64355
028 B020100 748
028 B030100 0
028 B040100 65007
028 C010100 84032
028 C020100 792
028 C030100 0
028 C040100 91318
028 D010100 104240
028 D020100 808
028 D030100 0
028 D040100 88151
028 E010100 114804
028 E020100 879
028 E030100 0
028 E040100 95862
028 F010100 109024
028 F020100 901
028 F030100 0
028 F040100 112639
028 G010100 549697
028 G020100 4959
028 G030100 0
028 G040100 541069
028 H000100 0
034 000100 Y
035 000100 68
036 A000100 N
036 B000100 0
<PAGE> PAGE 6
037 000100 N
038 000100 0
039 000100 N
040 000100 Y
041 000100 Y
042 A000100 0
042 B000100 0
042 C000100 0
042 D000100 100
042 E000100 0
042 F000100 0
042 G000100 0
042 H000100 0
043 000100 285
044 000100 0
049 000100 N
050 000100 N
051 000100 N
052 000100 N
053 A000100 N
055 A000100 N
055 B000100 N
056 000100 Y
057 000100 N
062 A000100 Y
062 B000100 0.0
062 C000100 14.5
062 D000100 0.0
062 E000100 0.0
062 F000100 0.0
062 G000100 0.0
062 H000100 0.0
062 I000100 78.8
062 J000100 0.0
062 K000100 0.0
062 L000100 5.7
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 26
063 B000100 0.0
064 A000100 N
064 B000100 N
066 A000100 N
067 000100 N
068 A000100 N
068 B000100 N
069 000100 N
<PAGE> PAGE 7
070 A010100 Y
070 A020100 Y
070 B010100 N
070 B020100 N
070 C010100 N
070 C020100 N
070 D010100 N
070 D020100 N
070 E010100 N
070 E020100 N
070 F010100 N
070 F020100 N
070 G010100 N
070 G020100 N
070 H010100 N
070 H020100 N
070 I010100 N
070 I020100 N
070 J010100 N
070 J020100 N
070 K010100 N
070 K020100 N
070 L010100 N
070 L020100 N
070 M010100 N
070 M020100 N
070 N010100 N
070 N020100 N
070 O010100 Y
070 O020100 N
070 P010100 N
070 P020100 N
070 Q010100 N
070 Q020100 N
070 R010100 N
070 R020100 N
071 A000100 0
071 B000100 0
071 C000100 0
071 D000100 0
072 A000100 6
072 B000100 6699
072 C000100 0
072 D000100 0
072 E000100 0
072 F000100 478
072 G000100 0
072 H000100 0
072 I000100 199
072 J000100 23
072 K000100 0
<PAGE> PAGE 8
072 L000100 10
072 M000100 6
072 N000100 60
072 O000100 0
072 P000100 0
072 Q000100 28
072 R000100 18
072 S000100 5
072 T000100 285
072 U000100 0
072 V000100 0
072 W000100 17
072 X000100 1129
072 Y000100 0
072 Z000100 5570
072AA000100 0
072BB000100 0
072CC010100 0
072CC020100 0
072DD010100 4915
072DD020100 655
072EE000100 0
073 A010100 0.0000
073 A020100 0.0000
073 B000100 0.0000
073 C000100 0.0000
074 A000100 1
074 B000100 0
074 C000100 259899
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 13671
074 M000100 1
074 N000100 273572
074 O000100 9500
074 P000100 287
074 Q000100 0
074 R010100 0
074 R020100 0
074 R030100 0
074 R040100 1142
074 S000100 0
074 T000100 262643
074 U010100 227334
074 U020100 35584
<PAGE> PAGE 9
074 V010100 0.00
074 V020100 0.00
074 W000100 0.9986
074 X000100 17911
074 Y000100 0
075 A000100 243180
075 B000100 0
076 000100 0.00
SIGNATURE ROBERT P. NAULT
TITLE ASST. SECRETARY
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000812195
<NAME> PIONEER CASH RESERVES FUND
<SERIES>
<NUMBER> 001
<NAME> PIONEER CASH RESERVES FUND CLASS A
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> JUN-30-1998
<INVESTMENTS-AT-COST> 259899470
<INVESTMENTS-AT-VALUE> 259899470
<RECEIVABLES> 13671304
<ASSETS-OTHER> 571
<OTHER-ITEMS-ASSETS> 1109
<TOTAL-ASSETS> 273572454
<PAYABLE-FOR-SECURITIES> 9500000
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 1429811
<TOTAL-LIABILITIES> 10929811
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 262918706
<SHARES-COMMON-STOCK> 227334406
<SHARES-COMMON-PRIOR> 209317304
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 276063
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 262642643
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 6699011
<OTHER-INCOME> 0
<EXPENSES-NET> 1129227
<NET-INVESTMENT-INCOME> 5569784
<REALIZED-GAINS-CURRENT> 0
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 5569784
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 4914874
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 439074241
<NUMBER-OF-SHARES-REDEEMED> 425450002
<SHARES-REINVESTED> 4392863
<NET-CHANGE-IN-ASSETS> 13587268
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 276063
<GROSS-ADVISORY-FEES> 477897
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1138101
<AVERAGE-NET-ASSETS> 209558309
<PER-SHARE-NAV-BEGIN> 1
<PER-SHARE-NII> .02
<PER-SHARE-GAIN-APPREC> 0
<PER-SHARE-DIVIDEND> .02
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1
<EXPENSE-RATIO> .84
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000812195
<NAME> PIONEER CASH RESERVES FUND
<SERIES>
<NUMBER> 002
<NAME> PIONEER CASH RESERVES FUND CLASS B
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> JUN-30-1998
<INVESTMENTS-AT-COST> 259899470
<INVESTMENTS-AT-VALUE> 259899470
<RECEIVABLES> 13671304
<ASSETS-OTHER> 571
<OTHER-ITEMS-ASSETS> 1109
<TOTAL-ASSETS> 273572454
<PAYABLE-FOR-SECURITIES> 9500000
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 1429811
<TOTAL-LIABILITIES> 10929811
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 262918706
<SHARES-COMMON-STOCK> 25101277
<SHARES-COMMON-PRIOR> 32477169
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 276063
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 262642643
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 6699011
<OTHER-INCOME> 0
<EXPENSES-NET> 1129227
<NET-INVESTMENT-INCOME> 5569784
<REALIZED-GAINS-CURRENT> 0
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 5569784
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 498717
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 34623363
<NUMBER-OF-SHARES-REDEEMED> 42441959
<SHARES-REINVESTED> 442704
<NET-CHANGE-IN-ASSETS> 13587268
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 276063
<GROSS-ADVISORY-FEES> 477897
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1138101
<AVERAGE-NET-ASSETS> 25692841
<PER-SHARE-NAV-BEGIN> 1
<PER-SHARE-NII> .02
<PER-SHARE-GAIN-APPREC> 0
<PER-SHARE-DIVIDEND> .02
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1
<EXPENSE-RATIO> 1.66
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<CIK> 0000812195
<NAME> PIONEER CASH RESERVES FUND
<SERIES>
<NUMBER> 003
<NAME> PIONEER CASH RESERVES FUND CLASS C
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1998
<PERIOD-END> JUN-30-1998
<INVESTMENTS-AT-COST> 259899470
<INVESTMENTS-AT-VALUE> 259899470
<RECEIVABLES> 13671304
<ASSETS-OTHER> 571
<OTHER-ITEMS-ASSETS> 1109
<TOTAL-ASSETS> 273572454
<PAYABLE-FOR-SECURITIES> 9500000
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 1429811
<TOTAL-LIABILITIES> 10929811
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 262918706
<SHARES-COMMON-STOCK> 10483023
<SHARES-COMMON-PRIOR> 7536965
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 276063
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 262642643
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 6699011
<OTHER-INCOME> 0
<EXPENSES-NET> 1129227
<NET-INVESTMENT-INCOME> 5569784
<REALIZED-GAINS-CURRENT> 0
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 5569784
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 156193
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 75999413
<NUMBER-OF-SHARES-REDEEMED> 73177227
<SHARES-REINVESTED> 123872
<NET-CHANGE-IN-ASSETS> 13587268
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 276063
<GROSS-ADVISORY-FEES> 477897
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1138101
<AVERAGE-NET-ASSETS> 7928486
<PER-SHARE-NAV-BEGIN> 1
<PER-SHARE-NII> .02
<PER-SHARE-GAIN-APPREC> 0
<PER-SHARE-DIVIDEND> .02
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1
<EXPENSE-RATIO> 1.61
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
