PAGE  1
000 A000000 06/30/2010
000 C000000 0000275694
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000 F000000 Y
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000 H000000 N
000 I000000 6.1
000 J000000 A
001 A000000 MASSMUTUAL CORPORATE INVESTORS
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001 C000000 4132261000
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002 B000000 SPRINGFIELD
002 C000000 MA
002 D010000 01115
002 D020000 5189
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008 B000001 A
008 C000001 801-241
008 D010001 SPRINGFIELD
008 D020001 MA
008 D030001 01115
008 D040001 5189
012 A000001 SHAREHOLDER FINANCIAL SERVICES, INC.
012 B000001 84-1817
012 C010001 CENTENNIAL
012 C020001 CO
012 C030001 80112
013 A000001 KPMG LLP
013 B010001 BOSTON
013 B020001 MA
013 B030001 02110
013 B040001 2371
014 A000001 BABSON CAPITAL SECURITIES INC
      PAGE  2
014 B000001 8-47589
014 A000002 MML INVESTOR SERVICES, INC.
014 B000002 8-27250
014 A000003 OPPENHEIMER DISTRIBUTOR, INC.
014 B000003 8-22992
014 A000004 MML DISTRIBUTORS, LLC
014 B000004 8-48203
015 A000001 CITIBANK, N.A.
015 B000001 C
015 C010001 NEW YORK
015 C020001 NY
015 C030001 10043
015 E010001 X
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019 C000000 CIPIINVEST
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020 C000005      0
020 C000006      0
020 C000007      0
020 C000008      0
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020 C000010      0
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022 B000001 23-3069627
022 C000001     23258
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022 A000002 BARCLAYS CAPITAL INC.
022 C000002     21617
022 D000002      3240
022 A000003 JP MORGAN CHASE
022 B000003 13-4994650
022 C000003     18398
022 D000003      2682
022 A000004 WACHOVIA SECURITIES LLC
022 B000004 34-1542819
022 C000004     10580
022 D000004      1967
022 A000005 SUNTRUST CAPITAL MARKET
022 C000005     10149
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022 A000006 GOLDMAN, SACHS & CO
022 B000006 13-5108880
022 C000006      8006
022 D000006      1766
022 A000007 CITIGROUP
      PAGE  3
022 B000007 13-3214963
022 C000007      8815
022 D000007       322
022 A000008 FIRST BOSTON CORP
022 B000008 13-5659485
022 C000008      5188
022 D000008      1159
022 A000009 MORGAN, STANLEY AND CO
022 C000009      5188
022 D000009      1159
022 A000010 DEUTSCHE BANK CAPITAL CORP.
022 B000010 13-2730828
022 C000010      2600
022 D000010       453
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      PAGE  4
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      PAGE  5
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      PAGE  6
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      PAGE  7
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      PAGE  8
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      PAGE  9
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SIGNATURE   JAMES M. ROY
TITLE       V.P. AND C.F.O.

                           EXHIBIT INDEX TO FORM N-SAR
                        OF MASSMUTUAL CORPORATE INVESTORS
                   FOR SEMI-ANNUAL PERIOD ENDED JUNE 30, 2010


EXHIBIT NO.                   DESCRIPTION

77Q1              By-Laws