<TABLE> <S> <C>

<ARTICLE> 6
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM JOHN HANCOCK
VARIABLE SERIES TRUST I AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS.
</LEGEND>
<CIK> 0000785303
<NAME> JOHN HANCOCK VARIABLE SERIES TRUST I
<SERIES>
   <NUMBER> 08
   <NAME> DIVERSIFIED MID CAP GROWTH
<MULTIPLIER> 1000
       
<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               JUN-30-1998
<INVESTMENTS-AT-COST>                          191,104
<INVESTMENTS-AT-VALUE>                         221,554
<RECEIVABLES>                                    1,281
<ASSETS-OTHER>                                       0
<OTHER-ITEMS-ASSETS>                                 1
<TOTAL-ASSETS>                                 222,836
<PAYABLE-FOR-SECURITIES>                         1,771
<SENIOR-LONG-TERM-DEBT>                              0
<OTHER-ITEMS-LIABILITIES>                           22
<TOTAL-LIABILITIES>                              1,793
<SENIOR-EQUITY>                                      0
<PAID-IN-CAPITAL-COMMON>                       183,528
<SHARES-COMMON-STOCK>                           12,989
<SHARES-COMMON-PRIOR>                           13,884
<ACCUMULATED-NII-CURRENT>                        1,458
<OVERDISTRIBUTION-NII>                               0
<ACCUMULATED-NET-GAINS>                         18,015
<OVERDISTRIBUTION-GAINS>                             0
<ACCUM-APPREC-OR-DEPREC>                        18,042
<NET-ASSETS>                                   221,043
<DIVIDEND-INCOME>                                  686
<INTEREST-INCOME>                                  222
<OTHER-INCOME>                                       0
<EXPENSES-NET>                                     937
<NET-INVESTMENT-INCOME>                           (29)
<REALIZED-GAINS-CURRENT>                        18,015
<APPREC-INCREASE-CURRENT>                        3,764
<NET-CHANGE-FROM-OPS>                           21,750
<EQUALIZATION>                                       0
<DISTRIBUTIONS-OF-INCOME>                            0
<DISTRIBUTIONS-OF-GAINS>                             0
<DISTRIBUTIONS-OTHER>                                0
<NUMBER-OF-SHARES-SOLD>                            598
<NUMBER-OF-SHARES-REDEEMED>                    (1,493)
<SHARES-REINVESTED>                                  0
<NET-CHANGE-IN-ASSETS>                           7,431
<ACCUMULATED-NII-PRIOR>                              0
<ACCUMULATED-GAINS-PRIOR>                            0
<OVERDISTRIB-NII-PRIOR>                              0
<OVERDIST-NET-GAINS-PRIOR>                           0
<GROSS-ADVISORY-FEES>                              808
<INTEREST-EXPENSE>                                   0
<GROSS-EXPENSE>                                    937
<AVERAGE-NET-ASSETS>                                 0
<PER-SHARE-NAV-BEGIN>                            15.39
<PER-SHARE-NII>                                      0
<PER-SHARE-GAIN-APPREC>                           1.63
<PER-SHARE-DIVIDEND>                                 0
<PER-SHARE-DISTRIBUTIONS>                            0
<RETURNS-OF-CAPITAL>                                 0
<PER-SHARE-NAV-END>                              17.02
<EXPENSE-RATIO>                                   0.86
<AVG-DEBT-OUTSTANDING>                               0
<AVG-DEBT-PER-SHARE>                                 0
        

</TABLE>