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<PAGE> PAGE 10
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<PAGE> PAGE 12
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<PAGE> PAGE 13
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<PAGE> PAGE 16
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<PAGE> PAGE 18
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025 C000502 E
025 D000502 108
025 A000503 MORGAN (J.P.)SECURITIES INC.
025 B000503 13-3224016
025 C000503 E
025 D000503 68
025 D000504 0
025 D000505 0
025 D000506 0
025 D000507 0
025 D000508 0
028 A010500 0
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<PAGE> PAGE 21
028 C040500 0
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028 F030500 0
028 F040500 0
028 G010500 24
028 G020500 0
028 G030500 0
028 G040500 0
028 H000500 0
045 000500 Y
046 000500 N
047 000500 Y
048 000500 0.000
048 A010500 100000
048 A020500 0.400
048 B010500 150000
048 B020500 0.380
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048 H010500 0
048 H020500 0.000
048 I010500 0
048 I020500 0.000
048 J010500 0
048 J020500 0.000
048 K010500 250000
048 K020500 0.360
055 A000500 N
055 B000500 N
056 000500 Y
057 000500 N
058 A000500 N
059 000500 Y
060 A000500 N
<PAGE> PAGE 22
060 B000500 N
061 000500 0
062 A000500 N
062 B000500 0.0
062 C000500 0.0
062 D000500 0.0
062 E000500 0.0
062 F000500 0.0
062 G000500 0.0
062 H000500 0.0
062 I000500 0.0
062 J000500 0.0
062 K000500 0.0
062 L000500 0.0
062 M000500 0.0
062 N000500 0.0
062 O000500 0.0
062 P000500 0.0
062 Q000500 0.0
062 R000500 0.0
063 A000500 0
063 B000500 0.0
066 A000500 Y
066 B000500 N
066 C000500 N
066 D000500 Y
066 E000500 N
066 F000500 N
066 G000500 N
067 000500 N
068 A000500 N
068 B000500 N
069 000500 Y
070 A010500 Y
070 A020500 N
070 B010500 Y
070 B020500 N
070 C010500 Y
070 C020500 N
070 D010500 Y
070 D020500 N
070 E010500 Y
070 E020500 N
070 F010500 Y
070 F020500 N
070 G010500 Y
070 G020500 N
070 H010500 Y
070 H020500 N
070 I010500 N
070 I020500 N
<PAGE> PAGE 23
070 J010500 N
070 J020500 N
070 K010500 Y
070 K020500 N
070 L010500 Y
070 L020500 N
070 M010500 N
070 M020500 N
070 N010500 Y
070 N020500 N
070 O010500 Y
070 O020500 N
070 P010500 N
070 P020500 N
070 Q010500 Y
070 Q020500 N
070 R010500 Y
070 R020500 N
071 A000500 20591
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072 A000500 8
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072 C000500 272
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<PAGE> PAGE 24
072CC020500 0
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073 A010500 0.0920
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SIGNATURE STEHPEN L. KUHN
TITLE SECRETARY
<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 YEAR ENDED
DECEMBER 31, 1997 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
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> DEC-31-1997
<PERIOD-START> JAN-01-1997
<PERIOD-END> DEC-31-1997
<INVESTMENTS-AT-COST> 1,637,676,544
<INVESTMENTS-AT-VALUE> 2,560,250,707
<RECEIVABLES> 6,947,231
<ASSETS-OTHER> 2,546,472
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 2,569,744,410
<PAYABLE-FOR-SECURITIES> 13,448,674
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 192,854,459
<TOTAL-LIABILITIES> 206,303,134
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,440,195,104
<SHARES-COMMON-STOCK> 66,682,603
<SHARES-COMMON-PRIOR> 57,140,244
<ACCUMULATED-NII-CURRENT> 16,996
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> (11,812)
<ACCUM-APPREC-OR-DEPREC> 922,574,163
<NET-ASSETS> 2,363,441,277
<DIVIDEND-INCOME> 47,216,639
<INTEREST-INCOME> 8,237,702
<OTHER-INCOME> 0
<EXPENSES-NET> 8,152,038
<NET-INVESTMENT-INCOME> 47,302,303
<REALIZED-GAINS-CURRENT> 143,291,448
<APPREC-INCREASE-CURRENT> 347,666,835
<NET-CHANGE-FROM-OPS> 538,260,585
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 47,301,234
<DISTRIBUTIONS-OF-GAINS> 143,291,448
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 9,271,802
<NUMBER-OF-SHARES-REDEEMED> 2,391,566
<SHARES-REINVESTED> 2,662,123
<NET-CHANGE-IN-ASSETS> 661,442,908
<ACCUMULATED-NII-PRIOR> 15,927
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> (11,812)
<GROSS-ADVISORY-FEES> 8,082,863
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 8,152,038
<AVERAGE-NET-ASSETS> 2,328,067,108
<PER-SHARE-NAV-BEGIN> 29.786
<PER-SHARE-NII> 0.709
<PER-SHARE-GAIN-APPREC> 7.806
<PER-SHARE-DIVIDEND> 0.709
<PER-SHARE-DISTRIBUTIONS> 2.149
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 35.443
<EXPENSE-RATIO> 0.35
<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 YEAR ENDED
DECEMBER 31, 1997 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
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> DEC-31-1997
<PERIOD-START> JAN-01-1997
<PERIOD-END> DEC-31-1997
<INVESTMENTS-AT-COST> 141,970,432
<INVESTMENTS-AT-VALUE> 141,970,432
<RECEIVABLES> 0
<ASSETS-OTHER> 2,550
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 141,972,982
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 807,597
<TOTAL-LIABILITIES> 807,597
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 139,753,731
<SHARES-COMMON-STOCK> 141,165,385
<SHARES-COMMON-PRIOR> 145,231,042
<ACCUMULATED-NII-CURRENT> 13,560
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 13,560
<ACCUM-APPREC-OR-DEPREC> 0
<NET-ASSETS> 141,165,385
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 8,109,728
<OTHER-INCOME> 0
<EXPENSES-NET> 755,401
<NET-INVESTMENT-INCOME> 7,354,327
<REALIZED-GAINS-CURRENT> (4,291)
<APPREC-INCREASE-CURRENT> 0
<NET-CHANGE-FROM-OPS> 7,350,036
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 7,350,036
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 149,151,177
<NUMBER-OF-SHARES-REDEEMED> 160,539,000
<SHARES-REINVESTED> 7,322,166
<NET-CHANGE-IN-ASSETS> (4,065,657)
<ACCUMULATED-NII-PRIOR> 9,702
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> (9,702)
<GROSS-ADVISORY-FEES> 703,344
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 755,401
<AVERAGE-NET-ASSETS> 145,189,638
<PER-SHARE-NAV-BEGIN> 1.00
<PER-SHARE-NII> 0.051
<PER-SHARE-GAIN-APPREC> 0
<PER-SHARE-DIVIDEND> 0.051
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 1.00
<EXPENSE-RATIO> 0.52
<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 YEAR ENDED
DECEMBER 31, 1997 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS
</LEGEND>
<CIK> 0000067160
<NAME> MML SERIES INVESTMENT FUND
<SERIES>
<NUMBER> 3
<NAME> MML MANAGED BOND FUND
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> DEC-31-1997
<PERIOD-START> JAN-01-1997
<PERIOD-END> DEC-31-1997
<INVESTMENTS-AT-COST> 199,796,030
<INVESTMENTS-AT-VALUE> 206,243,754
<RECEIVABLES> 2,612,660
<ASSETS-OTHER> 3,085
<OTHER-ITEMS-ASSETS> 1,119
<TOTAL-ASSETS> 208,860,618
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 3,544,721
<TOTAL-LIABILITIES> 3,544,721
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 198,798,225
<SHARES-COMMON-STOCK> 16,545,756
<SHARES-COMMON-PRIOR> 15,070,294
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> (96,215)
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 705
<ACCUM-APPREC-OR-DEPREC> 6,447,725
<NET-ASSETS> 205,315,898
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 13,560,239
<OTHER-INCOME> 0
<EXPENSES-NET> 970,874
<NET-INVESTMENT-INCOME> 12,589,365
<REALIZED-GAINS-CURRENT> 1,090,224
<APPREC-INCREASE-CURRENT> 4,682,107
<NET-CHANGE-FROM-OPS> 18,361,695
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 12,621,479
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 2,489,815
<NUMBER-OF-SHARES-REDEEMED> 2,025,213
<SHARES-REINVESTED> 1,010,861
<NET-CHANGE-IN-ASSETS> 23,743,613
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> (64,100)
<OVERDIST-NET-GAINS-PRIOR> (1,089,519)
<GROSS-ADVISORY-FEES> 913,026
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 970,874
<AVERAGE-NET-ASSETS> 207,742,519
<PER-SHARE-NAV-BEGIN> 12.048
<PER-SHARE-NII> 0.801
<PER-SHARE-GAIN-APPREC> 0.356
<PER-SHARE-DIVIDEND> 0.795
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 12.410
<EXPENSE-RATIO> 0.47
<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 YEAR ENDED
DECEMBER 31, 1997 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> YEAR
<FISCAL-YEAR-END> DEC-31-1997
<PERIOD-START> JAN-01-1997
<PERIOD-END> DEC-31-1997
<INVESTMENTS-AT-COST> 1,920,975,931
<INVESTMENTS-AT-VALUE> 2,661,619,219
<RECEIVABLES> 11,642,820
<ASSETS-OTHER> 1,344,963
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 2,674,607,002
<PAYABLE-FOR-SECURITIES> 15,073,387
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 187,706,124
<TOTAL-LIABILITIES> 202,779,511
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1,730,351,561
<SHARES-COMMON-STOCK> 102,652,434
<SHARES-COMMON-PRIOR> 95,296,912
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> (53,700)
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> (140,182)
<ACCUM-APPREC-OR-DEPREC> 740,643,288
<NET-ASSETS> 2,471,827,491
<DIVIDEND-INCOME> 33,425,435
<INTEREST-INCOME> 60,842,442
<OTHER-INCOME> 0
<EXPENSES-NET> 8,997,938
<NET-INVESTMENT-INCOME> 85,269,939
<REALIZED-GAINS-CURRENT> 162,884,955
<APPREC-INCREASE-CURRENT> 209,070,059
<NET-CHANGE-FROM-OPS> 457,224,953
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 85,322,771
<DISTRIBUTIONS-OF-GAINS> 162,679,164
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 6,389,317
<NUMBER-OF-SHARES-REDEEMED> 4,905,462
<SHARES-REINVESTED> 5,871,667
<NET-CHANGE-IN-ASSETS> 377,837,250
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> (870)
<OVERDIST-NET-GAINS-PRIOR> (345,972)
<GROSS-ADVISORY-FEES> 8,933,947
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 8,997,938
<AVERAGE-NET-ASSETS> 2,397,687,898
<PER-SHARE-NAV-BEGIN> 21.973
<PER-SHARE-NII> 0.843
<PER-SHARE-GAIN-APPREC> 3.692
<PER-SHARE-DIVIDEND> 0.843
<PER-SHARE-DISTRIBUTIONS> 1.585
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 24.080
<EXPENSE-RATIO> 0.38
<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 YEAR ENDED
DECEMBER 31, 1997 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> YEAR
<FISCAL-YEAR-END> DEC-31-1997
<PERIOD-START> JAN-01-1997
<PERIOD-END> DEC-31-1997
<INVESTMENTS-AT-COST> 20,306,016
<INVESTMENTS-AT-VALUE> 24,477,578
<RECEIVABLES> 40,884
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 24,518,462
<PAYABLE-FOR-SECURITIES> 4,327
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 312,372
<TOTAL-LIABILITIES> 316,699
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 20,009,993
<SHARES-COMMON-STOCK> 2,062,675
<SHARES-COMMON-PRIOR> 0
<ACCUMULATED-NII-CURRENT> 235
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> (53)
<ACCUM-APPREC-OR-DEPREC> 4,171,562
<NET-ASSETS> 24,201,763
<DIVIDEND-INCOME> 272,010
<INTEREST-INCOME> 12,011
<OTHER-INCOME> 0
<EXPENSES-NET> 99,423
<NET-INVESTMENT-INCOME> 184,598
<REALIZED-GAINS-CURRENT> 41,673
<APPREC-INCREASE-CURRENT> 4,171,562
<NET-CHANGE-FROM-OPS> 4,392,833
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 184,363
<DISTRIBUTIONS-OF-GAINS> 41,726
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 2,002,676
<NUMBER-OF-SHARES-REDEEMED> 1
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> 24,201,763
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 61,760
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 99,423
<AVERAGE-NET-ASSETS> 23,094,034
<PER-SHARE-NAV-BEGIN> 10
<PER-SHARE-NII> 0.092
<PER-SHARE-GAIN-APPREC> 2.101
<PER-SHARE-DIVIDEND> 0.092
<PER-SHARE-DISTRIBUTIONS> 0.021
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 12.08
<EXPENSE-RATIO> 0.64
<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 DECEMBER 31, 1997
Exhibit No. Description
77B Accountant's report on internal control
COOPERS COOPERS & LYBRAND L.L.P.
& LYBRAND a professional services firm
REPORT OF INDEPENDENT ACCOUNTANTS
To the Board of Trustees and Shareholders of
MML Series Investment Fund
In planning and performing our audit of the financial statements and financial
highlights of each of the funds which comprise the MML Series Investment Fund
for the year ended December 31, 1997, we considered its internal control,
including controls over safeguarding securities, in order to determine our
auditing procedures for the purpose of expressing our opinion on the financial
statements and financial highlights and to comply with the requirements of
Form N-SAR, not to provide assurance on the internal control.
The management of the MML Series Investment Fund is responsible for
establishing and maintaining internal control. In fulfilling this
responsibility, estimates and judgments by management are required to assess
the expected benefits and related costs of controls. Generally, controls that
are relevant to an audit pertain to the entity's objective of preparing
financial statements for external purposes that are fairly presented in
conformity with generally accepted accounting principles. Those controls
include the safeguarding of assets against unauthorized acquisition, use, or
disposition.
Because of inherent limitations in internal control, errors or irregularities
may occur and may not be detected. Also, projection of any evaluation of
internal control to future periods is subject to the risk that it may become
inadequate because of changes in conditions or that the effectiveness of the
design and operation may deteriorate.
Our consideration of internal control would not necessarily disclose all
matters in internal control that might be material weaknesses under standards
established by the American Institute of Certified Public Accountants. A
material weakness is a condition in which the design or operation of any
specific internal control component does not reduce to a relatively low level
the risk that errors or irregularities in amounts that would be material in
relation to the financial statements and financial highlights being audited
may occur and not be detected within a timely period by employees in the
normal course of performing their assigned functions. However, we noted no
matters involving internal control, including controls over safeguarding
securities, that we consider to be material weaknesses, as defined above as of
December 31, 1997.
This report is intended solely for the information and use of the Board of
Trustees and management of the MML Series Investment Fund and the Securities
and Exchange Commission.
COOPERS & LYBRAND L.L.P.
Springfield, Massachusetts
January 31, 1998
Coopers & Lybrand L.L.P is a member of Coopers & Lybrand International, a
limited liability association incorporated in Switzerland
