PAGE 1 000 A000000 04/30/2010 000 C000000 0001275214 000 D000000 N 000 E000000 NF 000 F000000 Y 000 G000000 N 000 H000000 N 000 I000000 6.1 000 J000000 A 001 A000000 CALAMOS STRATEGIC TOTAL RETURN FUND 001 B000000 811-21484 001 C000000 6302457200 002 A000000 2020 CALAMOS COURT 002 B000000 NAPERVILLE 002 C000000 IL 002 D010000 60563 003 000000 N 004 000000 N 005 000000 N 006 000000 N 007 A000000 N 007 B000000 0 007 C010100 1 008 A000001 CALAMOS ADVISORS LLC 008 B000001 A 008 C000001 801-29688 008 D010001 NAPERVILLE 008 D020001 IL 008 D030001 60563 010 A000001 State Street Bank and Trust Company 010 B000001 028-00733 010 C010001 Boston 010 C020001 MA 010 C030001 02111 012 A000001 BANK OF NEW YORK (COMMON) 012 B000001 85-05006 012 C010001 NEW YORK 012 C020001 NY 012 C030001 10286 013 A000001 Deloitte & Touche LLP 013 B010001 Chicago 013 B020001 IL 013 B030001 60606 014 A000001 CALAMOS FINANCIAL SERVICES LLC 014 B000001 8-37854 015 A000001 STATE STREET BANK & TRUST COMPANY 015 B000001 C 015 C010001 BOSTON 015 C020001 MA 015 C030001 02111 015 E010001 X PAGE 2 015 A000002 CITIBANK NA 015 B000002 S 015 C010002 SAO PAULO 015 D010002 BRAZIL 015 E040002 X 015 A000003 STANDARD CHARTERED BANK 015 B000003 S 015 C010003 KWUN TONG 015 D010003 HONG KONG 015 E040003 X 015 A000004 DEUTSCHE BANK, AG 015 B000004 S 015 C010004 PARIS 015 D010004 FRANCE 015 E040004 X 015 A000005 EUROCLEAR BANK 015 B000005 S 015 C010005 BRUSSELS 015 D010005 BELGIUM 015 E040005 X 015 A000006 STATE STREET BANK AND TRUST COMPANY 015 B000006 S 015 C010006 LONDON 015 D010006 UNITED KINGDOM 015 E040006 X 015 A000007 Standard Chartered PLC 015 B000007 S 015 C010007 Taipei 015 D010007 Taiwan 015 E040007 X 018 000000 Y 019 A000000 Y 019 B000000 19 019 C000000 CALAMOSINV 020 A000001 SUSQUEHANNA INVESTMENT GROUP 020 B000001 23-2454154 020 C000001 194 020 A000002 OPPENHEIMER AND CO. 020 B000002 13-321135 020 C000002 47 020 A000003 BANK OF AMERICA 020 B000003 56-0906609 020 C000003 37 020 A000004 CREDIT SUISSE FIRST BOSTON 020 B000004 13-2853402 020 C000004 23 020 A000005 Hibbard & O'Connor Securities 020 C000005 19 020 A000006 BLOOMBERG TRADEBOOK LLC 020 B000006 13-388028 020 C000006 14 PAGE 3 020 A000007 ITG, INC. 020 B000007 95-4339369 020 C000007 8 020 A000008 BARCLAYS GLOBAL INVESTORS SERVICES 020 B000008 94-3231066 020 C000008 7 020 A000009 KNIGHT SECURITIES 020 B000009 22-3660471 020 C000009 5 020 A000010 GOLDMAN, SACHS & CO. 020 B000010 13-5108880 020 C000010 1 021 000000 355 022 A000001 BARCLAYS GLOBAL INVESTORS SERVICES 022 B000001 94-3231066 022 C000001 26255 022 D000001 56632 022 A000002 J.P. MORGAN SECURITIES INC. 022 B000002 13-3224016 022 C000002 61233 022 D000002 17962 022 A000003 GOLDMAN, SACHS & CO. 022 B000003 13-5108880 022 C000003 31697 022 D000003 34172 022 A000004 CREDIT SUISSE 022 B000004 13-2853402 022 C000004 23097 022 D000004 29531 022 A000005 BNP PARIBAS 022 B000005 13-1929559 022 C000005 25570 022 D000005 22652 022 A000006 DEUTSCHE BANK SECURITIES, INC. 022 B000006 13-2730828 022 C000006 28094 022 D000006 11693 022 A000007 CITIGROUP GLOBAL MARKETS, INC. 022 B000007 11-2418191 022 C000007 11901 022 D000007 14846 022 A000008 BANK OF AMERICA SECURITIES LLC 022 B000008 56-2058405 022 C000008 15879 022 D000008 9136 022 A000009 BANK OF NEW YORK MELLON 022 B000009 13-3894751 022 C000009 13584 022 D000009 2025 022 A000010 JEFFERIES & CO INC 022 B000010 95-262290 PAGE 4 022 C000010 2196 022 D000010 8052 023 C000000 534727 023 D000000 492914 024 000000 Y 025 A000001 BANK OF AMERICA 025 B000001 56-0906609 025 C000001 E 025 D000001 51141 025 A000002 J.P. MORGAN SECURITIES INC. 025 B000002 13-3224016 025 C000002 E 025 D000002 48618 025 A000003 GOLDMAN, SACHS & CO. 025 B000003 13-5108880 025 C000003 E 025 D000003 11970 025 A000004 DEUTSCHE BANK SECURITIES, INC. 025 B000004 13-2730828 025 C000004 E 025 D000004 29797 025 A000005 CREDIT SUISSE FIRST BOSTON 025 B000005 13-2853402 025 C000005 E 025 D000005 21466 025 A000006 BNP PARIBAS 025 B000006 13-1929559 025 C000006 E 025 D000006 12519 025 A000007 BARCLAYS GLOBAL INVESTORS SERVICES 025 B000007 94-3231066 025 C000007 E 025 D000007 16197 025 A000008 CITIGROUP GLOBAL MARKETS, INC. 025 B000008 11-2418191 025 C000008 E 025 D000008 7549 026 A000000 N 026 B000000 Y 026 C000000 N 026 D000000 Y 026 E000000 N 026 F000000 N 026 G010000 N 026 G020000 N 026 H000000 N 027 000000 N 028 A010000 0 028 A020000 0 028 A030000 0 028 A040000 0 PAGE 5 028 B010000 0 028 B020000 0 028 B030000 0 028 B040000 0 028 C010000 0 028 C020000 0 028 C030000 0 028 C040000 0 028 D010000 0 028 D020000 0 028 D030000 0 028 D040000 0 028 E010000 0 028 E020000 0 028 E030000 0 028 E040000 0 028 F010000 0 028 F020000 0 028 F030000 0 028 F040000 0 028 G010000 0 028 G020000 0 028 G030000 0 028 G040000 0 028 H000000 0 030 A000000 0 030 B000000 0.00 030 C000000 0.00 031 A000000 0 031 B000000 0 032 000000 0 033 000000 0 035 000000 0 036 B000000 0 038 000000 0 042 A000000 0 042 B000000 0 042 C000000 0 042 D000000 0 042 E000000 0 042 F000000 0 042 G000000 0 042 H000000 0 043 000000 0 044 000000 0 045 000000 Y 046 000000 N 047 000000 Y 048 000000 1.000 048 A010000 0 048 A020000 0.000 PAGE 6 048 B010000 0 048 B020000 0.000 048 C010000 0 048 C020000 0.000 048 D010000 0 048 D020000 0.000 048 E010000 0 048 E020000 0.000 048 F010000 0 048 F020000 0.000 048 G010000 0 048 G020000 0.000 048 H010000 0 048 H020000 0.000 048 I010000 0 048 I020000 0.000 048 J010000 0 048 J020000 0.000 048 K010000 0 048 K020000 0.000 049 000000 N 050 000000 N 051 000000 N 052 000000 N 053 A000000 N 054 A000000 Y 054 B000000 Y 054 C000000 N 054 D000000 N 054 E000000 N 054 F000000 N 054 G000000 N 054 H000000 Y 054 I000000 N 054 J000000 Y 054 K000000 N 054 L000000 N 054 M000000 Y 054 N000000 N 054 O000000 N 055 A000000 N 055 B000000 Y 056 000000 Y 057 000000 N 058 A000000 N 059 000000 Y 060 A000000 Y 060 B000000 Y 061 000000 0 062 A000000 N 062 B000000 0.0 PAGE 7 062 C000000 0.0 062 D000000 0.0 062 E000000 0.0 062 F000000 0.0 062 G000000 0.0 062 H000000 0.0 062 I000000 0.0 062 J000000 0.0 062 K000000 0.0 062 L000000 0.0 062 M000000 0.0 062 N000000 0.0 062 O000000 0.0 062 P000000 0.0 062 Q000000 0.0 062 R000000 0.0 063 A000000 0 063 B000000 0.0 066 A000000 Y 066 B000000 N 066 C000000 N 066 D000000 N 066 E000000 N 066 F000000 N 066 G000000 Y 067 000000 N 068 A000000 N 068 B000000 N 069 000000 N 070 A010000 Y 070 A020000 N 070 B010000 Y 070 B020000 Y 070 C010000 Y 070 C020000 N 070 D010000 Y 070 D020000 Y 070 E010000 Y 070 E020000 N 070 F010000 Y 070 F020000 N 070 G010000 Y 070 G020000 N 070 H010000 Y 070 H020000 N 070 I010000 Y 070 I020000 N 070 J010000 Y 070 J020000 Y 070 K010000 Y 070 K020000 Y PAGE 8 070 L010000 Y 070 L020000 Y 070 M010000 Y 070 M020000 Y 070 N010000 Y 070 N020000 Y 070 O010000 Y 070 O020000 Y 070 P010000 Y 070 P020000 N 070 Q010000 N 070 Q020000 N 070 R010000 Y 070 R020000 N 071 A000000 240220 071 B000000 370540 071 C000000 1961368 071 D000000 12 072 A000000 6 072 B000000 27950 072 C000000 29072 072 D000000 0 072 E000000 111 072 F000000 10334 072 G000000 0 072 H000000 0 072 I000000 19 072 J000000 48 072 K000000 0 072 L000000 137 072 M000000 39 072 N000000 68 072 O000000 0 072 P000000 5608 072 Q000000 176 072 R000000 46 072 S000000 41 072 T000000 0 072 U000000 0 072 V000000 0 072 W000000 42 072 X000000 16555 072 Y000000 0 072 Z000000 40578 072AA000000 18915 072BB000000 35223 072CC010000 169482 072CC020000 0 072DD010000 48672 072DD020000 0 072EE000000 0 PAGE 9 073 A010000 0.3150 073 A020000 0.0000 073 B000000 0.0000 073 C000000 0.0000 074 A000000 54 074 B000000 0 074 C000000 12225 074 D000000 864447 074 E000000 125765 074 F000000 1058143 074 G000000 3526 074 H000000 0 074 I000000 63749 074 J000000 8622 074 K000000 0 074 L000000 16701 074 M000000 333 074 N000000 2153565 074 O000000 3871 074 P000000 1982 074 Q000000 539000 074 R010000 0 074 R020000 0 074 R030000 0 074 R040000 12504 074 S000000 0 074 T000000 1596208 074 U010000 154514 074 U020000 0 074 V010000 10.33 074 V020000 0.00 074 W000000 0.0000 074 X000000 118 074 Y000000 950737 075 A000000 0 075 B000000 1544882 076 000000 9.24 077 A000000 N 078 000000 N 080 C000000 0 081 B000000 0 082 B000000 0 083 B000000 0 084 B000000 0 086 A010000 0 086 A020000 0 086 B010000 0 086 B020000 0 086 C010000 0 086 C020000 0 086 D010000 0 PAGE 10 086 D020000 0 086 E010000 0 086 E020000 0 086 F010000 0 086 F020000 0 087 A010000 COMMON STOCK 087 A020000 128125101 087 A030000 CSQ 088 A000000 N 088 B000000 N 088 C000000 Y 088 D000000 N SIGNATURE NIMISH BHATT TITLE CHIEF FINANCIAL OFFICER