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<PAGE> PAGE 21
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<PAGE> PAGE 22
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<PAGE> PAGE 23
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<PAGE> PAGE 24
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<PAGE> PAGE 25
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<PAGE> PAGE 26
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<PAGE> PAGE 27
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<PAGE> PAGE 28
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008 A000601 MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
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<PAGE> PAGE 29
008 D030601 01111
008 A000602 DAVID L. BABSON AND COMPANY INCORPORATED
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008 D020602 MA
008 D030602 02142
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015 A000601 CITIBANK, N.A.
015 B000601 C
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<PAGE> PAGE 30
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<PAGE> PAGE 31
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<PAGE> PAGE 32
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<PAGE> PAGE 33
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SIGNATURE CHARLES C. MCCOBB, JR.
TITLE VICE PRESIDENT
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
THE SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
REPORT TO SHAREHOLDERS OF MML SERIES INVESTMENT FUND FOR THE SIX MONTHS
ENDED JUNE 30, 1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS.
</LEGEND>
<CIK> 0000067160
<NAME> MML SERIES INVESTMENT FUND
<SERIES>
<NUMBER> 1
<NAME> MML EQUITY FUND
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</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
THE SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
REPORT TO SHAREHOLDERS OF MML SERIES INVESTMENT FUND FOR THE SIX MONTHS
ENDED JUNE 30, 1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS.
</LEGEND>
<CIK> 0000067160
<NAME> MML SERIES INVESTMENT FUND
<SERIES>
<NUMBER> 2
<NAME> MML MONEY MARKET FUND
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<PER-SHARE-DIVIDEND> (0.021)
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</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
THE SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
REPORT TO SHAREHOLDERS OF MML SERIES INVESTMENT FUND FOR THE SIX MONTHS
ENDED JUNE 30, 1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
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</LEGEND>
<CIK> 0000067160
<NAME> MML SERIES INVESTMENT FUND
<SERIES>
<NUMBER> 3
<NAME> MML MANAGED BOND FUND
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<EXPENSES-NET> 537,169
<NET-INVESTMENT-INCOME> 6,667,152
<REALIZED-GAINS-CURRENT> 365,750
<APPREC-INCREASE-CURRENT> 1,819,470
<NET-CHANGE-FROM-OPS> 8,852,372
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (3,309,276)
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 1,354,951
<NUMBER-OF-SHARES-REDEEMED> 764,645
<SHARES-REINVESTED> 530,483
<NET-CHANGE-IN-ASSETS> 19,595,635
<ACCUMULATED-NII-PRIOR> (96,215)
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 705
<GROSS-ADVISORY-FEES> 506,725
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 537,169
<AVERAGE-NET-ASSETS> 215,972,697
<PER-SHARE-NAV-BEGIN> 12.410
<PER-SHARE-NII> 0.383
<PER-SHARE-GAIN-APPREC> 0.131
<PER-SHARE-DIVIDEND> (0.193)
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 12.731
<EXPENSE-RATIO> 0.25
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
THE SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
REPORT TO SHAREHOLDERS OF MML SERIES INVESTMENT FUND FOR THE SIX MONTHS
ENDED JUNE 30, 1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS.
</LEGEND>
<CIK> 0000067160
<NAME> MML SERIES INVESTMENT FUND
<SERIES>
<NUMBER> 4
<NAME> MML BLEND FUND
<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> 2,098,865,319
<INVESTMENTS-AT-VALUE> 2,847,159,400
<RECEIVABLES> 10,774,559
<ASSETS-OTHER> 89,015
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 2,858,022,974
<PAYABLE-FOR-SECURITIES> 80,540
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 2,609,114
<TOTAL-LIABILITIES> 2,689,654
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,952,281,891
<SHARES-COMMON-STOCK> 111,735,238
<SHARES-COMMON-PRIOR> 102,652,434
<ACCUMULATED-NII-CURRENT> 24,680,960
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 130,076,388
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 748,294,081
<NET-ASSETS> 2,855,333,320
<DIVIDEND-INCOME> 17,620,768
<INTEREST-INCOME> 34,752,616
<OTHER-INCOME> 0
<EXPENSES-NET> 5,122,750
<NET-INVESTMENT-INCOME> 47,250,634
<REALIZED-GAINS-CURRENT> 130,216,571
<APPREC-INCREASE-CURRENT> 7,650,793
<NET-CHANGE-FROM-OPS> 185,117,998
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (22,515,974)
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 3,539,648
<NUMBER-OF-SHARES-REDEEMED> 3,020,661
<SHARES-REINVESTED> 8,563,817
<NET-CHANGE-IN-ASSETS> 383,505,829
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> (53,700)
<OVERDIST-NET-GAINS-PRIOR> (140,182)
<GROSS-ADVISORY-FEES> 5,087,148
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 5,122,750
<AVERAGE-NET-ASSETS> 2,794,487,972
<PER-SHARE-NAV-BEGIN> 24.08
<PER-SHARE-NII> 0.425
<PER-SHARE-GAIN-APPREC> 1.253
<PER-SHARE-DIVIDEND> 0.204
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 25.554
<EXPENSE-RATIO> 0.19
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
THE SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
REPORT TO SHAREHOLDERS OF MML SERIES INVESTMENT FUND FOR THE SIX MONTHS
ENDED JUNE 30, 1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS.
</LEGEND>
<CIK> 0000067160
<NAME> MML SERIES INVESTMENT FUND
<SERIES>
<NUMBER> 5
<NAME> MML EQUITY INDEX FUND
<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> 22,260,088
<INVESTMENTS-AT-VALUE> 30,630,492
<RECEIVABLES> 62,209
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 1,529
<TOTAL-ASSETS> 30,694,230
<PAYABLE-FOR-SECURITIES> 17,040
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 124,098
<TOTAL-LIABILITIES> 141,138
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 21,973,706
<SHARES-COMMON-STOCK> 2,149,430
<SHARES-COMMON-PRIOR> 2,002,675
<ACCUMULATED-NII-CURRENT> 156,027
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 52,955
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 8,370,404
<NET-ASSETS> 30,553,092
<DIVIDEND-INCOME> 206,381
<INTEREST-INCOME> 3,519
<OTHER-INCOME> 0
<EXPENSES-NET> 54,108
<NET-INVESTMENT-INCOME> 155,792
<REALIZED-GAINS-CURRENT> 53,008
<APPREC-INCREASE-CURRENT> 4,198,842
<NET-CHANGE-FROM-OPS> 4,407,642
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 128,270
<NUMBER-OF-SHARES-REDEEMED> 231
<SHARES-REINVESTED> 18,716
<NET-CHANGE-IN-ASSETS> 6,351,329
<ACCUMULATED-NII-PRIOR> 235
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 53
<GROSS-ADVISORY-FEES> 55,239
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 83,806
<AVERAGE-NET-ASSETS> 27,881,000
<PER-SHARE-NAV-BEGIN> 12.08
<PER-SHARE-NII> 0.072
<PER-SHARE-GAIN-APPREC> 2.058
<PER-SHARE-DIVIDEND> 0
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 14.21
<EXPENSE-RATIO> 0.40
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
THE SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
REPORT TO SHAREHOLDERS OF MML SERIES INVESTMENT FUND FOR THE SIX MONTHS
ENDED JUNE 30, 1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS.
</LEGEND>
<CIK> 0000067160
<NAME> MML SERIES INVESTMENT FUND
<SERIES>
<NUMBER> 6
<NAME> MML SMALL CAP VALUE EQUITY FUND
<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> 8,399,959
<INVESTMENTS-AT-VALUE> 8,255,104
<RECEIVABLES> 116,014
<ASSETS-OTHER> 1,479,632
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 9,850,750
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 8,215
<TOTAL-LIABILITIES> 8,215
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 10,000,000
<SHARES-COMMON-STOCK> 1,000,000
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 46
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> (12,656)
<ACCUM-APPREC-OR-DEPREC> (144,855)
<NET-ASSETS> 9,842,535
<DIVIDEND-INCOME> 6,138
<INTEREST-INCOME> 0
<OTHER-INCOME> 0
<EXPENSES-NET> 6,092
<NET-INVESTMENT-INCOME> 46
<REALIZED-GAINS-CURRENT> (12,656)
<APPREC-INCREASE-CURRENT> (144,855)
<NET-CHANGE-FROM-OPS> (157,465)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 1,000,000
<NUMBER-OF-SHARES-REDEEMED> 0
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 9,842,535
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 5,210
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 8,215
<AVERAGE-NET-ASSETS> 9,752
<PER-SHARE-NAV-BEGIN> 10.00
<PER-SHARE-NII> 0
<PER-SHARE-GAIN-APPREC> (0.157)
<PER-SHARE-DIVIDEND> 0
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 9.84
<EXPENSE-RATIO> 0.06
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
</TABLE>
EXHIBIT INDEX TO FORM N-SAR
OF MML SERIES INVESTMENT FUND
FOR THE PERIOD ENDED JUNE 30, 1998
Exhibit No. Description
77Q(1)(e) Investment Management Agreement dated May 29, 1998
between MML Series Investment Fund on behalf of MML Small Cap
Value Equity Fund and Massachusetts Mutual Life Insurance
Company.
Investment Sub-Advisory Agreement effective as of May 29, 1998,
between Massachusetts Mutual Life Insurance Company and David L.
Babson and Company Incorporated regarding MML Small Cap Value
Equity Fund.
For Period Ended 06/30/98
File No. 811-2224
77Q(1)(e) Investment Management Agreement dated May 29, 1998
between MML Series Investment Fund on behalf of MML Small
Cap Value Equity Fund and Massachusetts Mutual Life Insurance
Company was filed as Exhibit No. 5A to Post-Effective
Amendment No. 40 to Registrant's Registration Statement on
Form N-1A (as filed with the Securities and Exchange
Commission ("SEC") via EDGAR), and is incorporated herein
by reference.
Investment Sub-Advisory Agreement effective as of May 29, 1998,
between Massachusetts Mutual Life Insurance Company and David L.
Babson and Company Incorporated regarding MML Small Cap Value
Equity Fund was filed as Exhibit No. 5B to Post-Effective
Amendment No. 40 to Registrant's Registration Statement on
Form N-1A (as filed with the SEC via EDGAR), and is incorporated
herein by reference.
