WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000320282
<NAME> Smith Barney Municipal Money Market Fund, Inc.

<S>                             <C>
<PERIOD-TYPE>                  6-MOS
<FISCAL-YEAR-END>                               Mar-31-2001
<PERIOD-END>                                    Sep-30-2000
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<INVESTMENTS-AT-VALUE>                        7,435,293,615
<RECEIVABLES>                                    49,176,022
<ASSETS-OTHER>                                      453,728
<OTHER-ITEMS-ASSETS>                                      0
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<PAYABLE-FOR-SECURITIES>                        319,032,050
<SENIOR-LONG-TERM-DEBT>                                   0
<OTHER-ITEMS-LIABILITIES>                        19,504,147
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<SENIOR-EQUITY>                                           0
<PAID-IN-CAPITAL-COMMON>                      7,146,558,611
<SHARES-COMMON-STOCK>                         7,145,988,994
<SHARES-COMMON-PRIOR>                         7,003,528,026
<ACCUMULATED-NII-CURRENT>                                 0
<OVERDISTRIBUTION-NII>                                    0
<ACCUMULATED-NET-GAINS>                                   0
<OVERDISTRIBUTION-GAINS>                                  0
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<DIVIDEND-INCOME>                                         0
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<OTHER-INCOME>                                            0
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<EQUALIZATION>                                            0
<DISTRIBUTIONS-OF-INCOME>                       130,046,547
<DISTRIBUTIONS-OF-GAINS>                                  0
<DISTRIBUTIONS-OTHER>                                     0
<NUMBER-OF-SHARES-SOLD>                                   0
<NUMBER-OF-SHARES-REDEEMED>                               0
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<ACCUMULATED-NII-PRIOR>                                   0
<ACCUMULATED-GAINS-PRIOR>                          (527,759)
<OVERDISTRIB-NII-PRIOR>                                   0
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<EXPENSE-RATIO>                                        0.63



</TABLE>