[ARTICLE] 6
[CIK] 0000880583
[NAME] THE TRAVELERS SERIES TUST
[SERIES]
   [NUMBER] 18
   [NAME] MFS MID CAP GROWTH PORTFOLIO
<TABLE>
<S>                             <C>
[PERIOD-TYPE]                   YEAR
[FISCAL-YEAR-END]                          DEC-31-1998
[PERIOD-END]                               DEC-31-1998
[INVESTMENTS-AT-COST]                       12,260,763
[INVESTMENTS-AT-VALUE]                      13,315,471
[RECEIVABLES]                                  110,822
[ASSETS-OTHER]                                   4,771
[OTHER-ITEMS-ASSETS]                                 0
[TOTAL-ASSETS]                              13,431,064
[PAYABLE-FOR-SECURITIES]                       162,115
[SENIOR-LONG-TERM-DEBT]                              0
[OTHER-ITEMS-LIABILITIES]                       35,136
[TOTAL-LIABILITIES]                            197,251
[SENIOR-EQUITY]                                      0
[PAID-IN-CAPITAL-COMMON]                    12,192,420
[SHARES-COMMON-STOCK]                        1,316,229
[SHARES-COMMON-PRIOR]                                0
[ACCUMULATED-NII-CURRENT]                            0
[OVERDISTRIBUTION-NII]                               0
[ACCUMULATED-NET-GAINS]                        (13,315)
[OVERDISTRIBUTION-GAINS]                             0
[ACCUM-APPREC-OR-DEPREC]                     1,054,708
[NET-ASSETS]                                13,233,813
[DIVIDEND-INCOME]                               11,903
[INTEREST-INCOME]                               27,404
[OTHER-INCOME]                                       0
[EXPENSES-NET]                                  52,388
[NET-INVESTMENT-INCOME]                        (13,081)
[REALIZED-GAINS-CURRENT]                          (234)
[APPREC-INCREASE-CURRENT]                    1,054,708
[NET-CHANGE-FROM-OPS]                        1,041,393
[EQUALIZATION]                                       0
[DISTRIBUTIONS-OF-INCOME]                            0
[DISTRIBUTIONS-OF-GAINS]                             0
[DISTRIBUTIONS-OTHER]                                0
[NUMBER-OF-SHARES-SOLD]                      1,328,144
[NUMBER-OF-SHARES-REDEEMED]                     11,915
[SHARES-REINVESTED]                                  0
[NET-CHANGE-IN-ASSETS]                      13,233,813
[ACCUMULATED-NII-PRIOR]                              0
[ACCUMULATED-GAINS-PRIOR]                            0
[OVERDISTRIB-NII-PRIOR]                              0
[OVERDIST-NET-GAINS-PRIOR]                           0
[GROSS-ADVISORY-FEES]                           41,903
[INTEREST-EXPENSE]                                   0
[GROSS-EXPENSE]                                 85,022
[AVERAGE-NET-ASSETS]                         5,237,875          
[PER-SHARE-NAV-BEGIN]                            10.00
[PER-SHARE-NII]                                 (00.02)
[PER-SHARE-GAIN-APPREC]                          00.07
[PER-SHARE-DIVIDEND]                             00.00
[PER-SHARE-DISTRIBUTIONS]                        00.00
[RETURNS-OF-CAPITAL]                                 0
[PER-SHARE-NAV-END]                              10.05
[EXPENSE-RATIO]                                  01.00
[AVG-DEBT-OUTSTANDING]                               0
[AVG-DEBT-PER-SHARE]                                 0
</TABLE>