<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 7
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM C.M. LIFE'S
SEPTEMBER 30, 1998 FINANCIAL STATEMENTS AND IS QUALIFIED IN ITS ENTIRETY BY
REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<CIK> 0000883232
<NAME> C.M. LIFE INSURANCE COMPANY
<MULTIPLIER> 1,000,000
       
<S>                             <C>
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-END>                               SEP-30-1998
<DEBT-HELD-FOR-SALE>                               649
<DEBT-CARRYING-VALUE>                                0
<DEBT-MARKET-VALUE>                                  0
<EQUITIES>                                          63
<MORTGAGE>                                         103
<REAL-ESTATE>                                        0
<TOTAL-INVEST>                                   1,121
<CASH>                                             150
<RECOVER-REINSURE>                                   3
<DEFERRED-ACQUISITION>                               0
<TOTAL-ASSETS>                                   2,348
<POLICY-LOSSES>                                    965
<UNEARNED-PREMIUMS>                                  0
<POLICY-OTHER>                                       5
<POLICY-HOLDER-FUNDS>                              969
<NOTES-PAYABLE>                                      0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                             3
<OTHER-SE>                                         149
<TOTAL-LIABILITY-AND-EQUITY>                     2,348
<PREMIUMS>                                         290
<INVESTMENT-INCOME>                                 61
<INVESTMENT-GAINS>                                   0
<OTHER-INCOME>                                      10
<BENEFITS>                                         250
<UNDERWRITING-AMORTIZATION>                          0
<UNDERWRITING-OTHER>                                77
<INCOME-PRETAX>                                     23
<INCOME-TAX>                                         7
<INCOME-CONTINUING>                                 16
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                        15
<EPS-PRIMARY>                                        0
<EPS-DILUTED>                                        0
<RESERVE-OPEN>                                       0
<PROVISION-CURRENT>                                  0
<PROVISION-PRIOR>                                    0
<PAYMENTS-CURRENT>                                   0
<PAYMENTS-PRIOR>                                     0
<RESERVE-CLOSE>                                      0
<CUMULATIVE-DEFICIENCY>                              0
<FN>
<F1>
C.M. LIFE'S FINANCIAL STATEMENTS HAVE BEEN PREPARED IN CONFORMITY WITH 
ACCOUNTING PRACTICES AND PROCEDURES OF THE NATIONAL ASSOCIATION OF INSURANCE 
COMMISSIONERS AS PRESCRIBED OR PERMITTED BY THE INSURANCE DEPARTMENT OF THE 
STATE OF CONNECTICUT. UNDER THESE ACCOUNTING PRACTICES, FIXED MATURITIES 
ELIGIBLE FOR AMORTIZATION ARE REPORTED AT AMORTIZED COST.
</FN>
        

</TABLE>