[ARTICLE] 6
[CIK] 0000320282
[NAME] SMITH BARNEY MUNICIPAL MONEY MARKET FUND, INC. CLASS Y
<TABLE>
<S>                             <C>
[PERIOD-TYPE]                   YEAR
[FISCAL-YEAR-END]                          MAR-31-1997
[PERIOD-END]                               MAR-31-1997
[INVESTMENTS-AT-COST]                    5,488,577,006
[INVESTMENTS-AT-VALUE]                   5,488,577,006
[RECEIVABLES]                               88,345,381
[ASSETS-OTHER]                                 161,111
[OTHER-ITEMS-ASSETS]                                 0
[TOTAL-ASSETS]                           5,577,083,498
[PAYABLE-FOR-SECURITIES]                             0
[SENIOR-LONG-TERM-DEBT]                              0
[OTHER-ITEMS-LIABILITIES]                   10,166,511
[TOTAL-LIABILITIES]                         10,166,511
[SENIOR-EQUITY]                                      0
[PAID-IN-CAPITAL-COMMON]                             0
[SHARES-COMMON-STOCK]                        4,755,401
[SHARES-COMMON-PRIOR]                                0
[ACCUMULATED-NII-CURRENT]                            0
[OVERDISTRIBUTION-NII]                               0
[ACCUMULATED-NET-GAINS]                              0
[OVERDISTRIBUTION-GAINS]                             0
[ACCUM-APPREC-OR-DEPREC]                             0
[NET-ASSETS]                             5,566,916,987
[DIVIDEND-INCOME]                                    0
[INTEREST-INCOME]                          192,373,989
[OTHER-INCOME]                                       0
[EXPENSES-NET]                              36,099,734
[NET-INVESTMENT-INCOME]                    156,274,255
[REALIZED-GAINS-CURRENT]                             0
[APPREC-INCREASE-CURRENT]                            0
[NET-CHANGE-FROM-OPS]                      156,205,821
[EQUALIZATION]                                       0
[DISTRIBUTIONS-OF-INCOME]                      659,522
[DISTRIBUTIONS-OF-GAINS]                             0
[DISTRIBUTIONS-OTHER]                                0
[NUMBER-OF-SHARES-SOLD]                     92,552,190
[NUMBER-OF-SHARES-REDEEMED]                106,276,754
[SHARES-REINVESTED]                            670,860
[NET-CHANGE-IN-ASSETS]                     153,563,358
[ACCUMULATED-NII-PRIOR]                              0
[ACCUMULATED-GAINS-PRIOR]                            0
[OVERDISTRIB-NII-PRIOR]                              0
[OVERDIST-NET-GAINS-PRIOR]                           0
[GROSS-ADVISORY-FEES]                       26,073,153
[INTEREST-EXPENSE]                                   0
[GROSS-EXPENSE]                             36,099,734
[AVERAGE-NET-ASSETS]                        22,011,994
[PER-SHARE-NAV-BEGIN]                             1.00
[PER-SHARE-NII]                                   .030
[PER-SHARE-GAIN-APPREC]                              0
[PER-SHARE-DIVIDEND]                            (.030)
[PER-SHARE-DISTRIBUTIONS]                            0
[RETURNS-OF-CAPITAL]                                 0
[PER-SHARE-NAV-END]                               1.00
[EXPENSE-RATIO]                                   0.57
[AVG-DEBT-OUTSTANDING]                               0
[AVG-DEBT-PER-SHARE]                                 0
</TABLE>