PAGE 1 000 B000000 07/31/2004 000 C000000 0001059386 000 D000000 N 000 E000000 NF 000 F000000 Y 000 G000000 N 000 H000000 N 000 I000000 6.1 000 J000000 A 001 A000000 VAN KAMPEN SENIOR INCOME TRUST 001 B000000 811-08743 001 C000000 2127625260 002 A000000 1221 AVENUE OF THE AMERICAS 002 B000000 NEW YORK 002 C000000 NY 002 D010000 10020 003 000000 N 004 000000 N 005 000000 N 006 000000 N 007 A000000 N 007 B000000 0 007 C010100 1 007 C010200 2 007 C010300 3 007 C010400 4 007 C010500 5 007 C010600 6 007 C010700 7 007 C010800 8 007 C010900 9 007 C011000 10 007 C011100 11 007 C011200 12 007 C011300 13 007 C011400 14 007 C011500 15 007 C011600 16 007 C011700 17 007 C011800 18 007 C011900 19 007 C012000 20 007 C012100 21 007 C012200 22 007 C012300 23 007 C012400 24 007 C012500 25 007 C012600 26 007 C012700 27 007 C012800 28 007 C012900 29 PAGE 2 007 C013000 30 007 C013100 31 007 C013200 32 007 C013300 33 007 C013400 34 007 C013500 35 007 C013600 36 007 C013700 37 007 C013800 38 007 C013900 39 007 C014000 40 008 A000001 VAN KAMPEN ASSET MANAGEMENT 008 B000001 A 008 C000001 801-1669 008 D010001 NEW YORK 008 D020001 NY 008 D030001 10020 010 A000001 VAN KAMPEN INVESTMENTS INC 010 B000001 8-19412 010 C010001 NEW YORK 010 C020001 NY 010 C030001 10020 012 A000001 STATE STREET BANK & TRUST CO. C/O EQUISERVE 012 B000001 85-11340 012 C010001 PROVIDENCE 012 C020001 RI 012 C030001 02940 012 C040001 3011 013 A000001 DELOITTE & TOUCHE LLP 013 B010001 CHICAGO 013 B020001 IL 013 B030001 60601 014 A000001 ARAB MALAYSIA SECURTIES 014 B000001 8-00000 014 A000002 CHINA INTERNATIONAL CAPITAL CORP. LTD 014 B000002 8-00000 014 A000003 HC SECURTITIES 014 B000003 8-00000 014 A000004 JM MORGAN STANLEY FIXED INCOME SEC. PRIV. LTD 014 B000004 8-00000 014 A000005 JM MORGAN STANLEY PRIVATE LTD 014 B000005 8-00000 014 A000006 JM MORGAN STANLEY SECURITIES PRIVATE LTD 014 B000006 8-00000 014 A000007 JM MORGAN STANLEY RETAIL SERVICES PRIV. LTD 014 B000007 8-00000 014 A000008 MORGAN STANLEY & CO. INC. 014 B000008 8-15869 014 A000009 MORGAN STANLEY & CO. LTD 014 B000009 8-00000 014 A000010 MORGAN STANLEY ASIA LTD PAGE 3 014 B000010 8-00000 014 A000011 MORGAN STANLEY CANADA LTD 014 B000011 8-00000 014 A000012 MORGAN STANLEY QUILTER LTD 014 B000012 8-00000 014 A000013 MORGAN STANLEY DW AUSTRALIA SEC. LTD 014 B000013 8-00000 014 A000014 MORGAN STANLEY JAPAN LTD 014 B000014 8-00000 014 A000015 MORGAN STANLEY NIPPON SECURITIES LTD 014 B000015 8-00000 014 A000016 MORGAN STANELY SV SA 014 B000016 8-00000 014 A000017 MORGAN STANELY DW INC. 014 B000017 8-14172 014 A000018 MORGAN STANLEY INTERNATIONAL LTD 014 B000018 8-00000 014 A000019 MORGAN STANLEY SECURITIES LTD 014 B000019 8-00000 014 A000020 MORGAN STANLEY BANK AG 014 B000020 8-00000 014 A000021 MORGAN STANLEY DISTRIBUTION INC. 014 B000021 8-44766 014 A000022 MORGAN STANLEY DISTRIBUTORS INC. 014 B000022 8-45262 014 A000023 MORGAN STANLEY MARKET PRODUCTS INC. 014 B000023 8-37795 014 A000024 MS SECURITIES SERVICES INC. 014 B000024 8-26804 014 A000025 PRIME DEALER SERVICES CORP. 014 B000025 8-47025 014 A000026 VAN KAMPEN FUNDS INC. 014 B000026 8-19412 015 A000001 STATE STREET BANK AND TRUST CO. 015 B000001 C 015 C010001 BOSTON 015 C020001 MA 015 C030001 02110 015 C040001 1713 015 E010001 X 018 000000 Y 019 A000000 Y 019 B000000 85 019 C000000 VANKAMPENF 020 A000001 JEFFERIES CO INC 020 B000001 95-2622900 020 C000001 67 020 A000002 LEHMAN BROTHERS INC. 020 B000002 13-2518466 020 C000002 24 020 A000003 CREDIT SUISSE FIRST BOSTON CO PAGE 4 020 B000003 13-5659485 020 C000003 22 020 A000004 ANTHONY J RINELLA 020 C000004 4 020 A000005 CANTOR FITZGERALD CO 020 C000005 4 020 A000006 UBS SECURITIES CANADA INC 020 C000006 3 020 C000007 0 020 C000008 0 020 C000009 0 020 C000010 0 021 000000 127 022 A000001 STATE STREET BANK 022 B000001 04-1867445 022 C000001 9092870 022 D000001 18894 022 A000002 JP MORGAN CHASE 022 B000002 13-3224016 022 C000002 999307 022 D000002 114544 022 A000003 BANK OF AMERICA 022 B000003 95-4035346 022 C000003 363211 022 D000003 54470 022 A000004 CITIBANK 022 C000004 261538 022 D000004 63308 022 A000005 DEUTSCHE BANK AG 022 B000005 13-2730828 022 C000005 224652 022 D000005 31924 022 A000006 CREDIT SUISSE FIRST BOSTON 022 B000006 13-5659485 022 C000006 175372 022 D000006 62254 022 A000007 WACHOVIA BANK 022 B000007 56-0276690 022 C000007 166798 022 D000007 7969 022 A000008 LEHMAN BROTHERS 022 B000008 13-2518466 022 C000008 132043 022 D000008 55645 022 A000009 BANK OF NEW YORK 022 B000009 13-5160382 022 C000009 47594 022 D000009 25714 022 A000010 UBS AG 022 B000010 13-2932996 022 C000010 45188 PAGE 5 022 D000010 11261 023 C000000 11918901 023 D000000 499257 024 000000 N 025 D000001 0 025 D000002 0 025 D000003 0 025 D000004 0 025 D000005 0 025 D000006 0 025 D000007 0 025 D000008 0 026 A000000 N 026 B000000 Y 026 C000000 Y 026 D000000 Y 026 E000000 N 026 F000000 Y 026 G010000 N 026 G020000 N 026 H000000 N 027 000000 N 028 A010000 0 028 A020000 0 028 A030000 0 028 A040000 0 028 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 PAGE 6 030 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 0.850 048 A010000 0 048 A020000 0.000 048 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 PAGE 7 054 A000000 Y 054 B000000 N 054 C000000 N 054 D000000 N 054 E000000 N 054 F000000 N 054 G000000 Y 054 H000000 Y 054 I000000 N 054 J000000 Y 054 K000000 N 054 L000000 N 054 M000000 Y 054 N000000 N 054 O000000 Y 055 A000000 N 055 B000000 Y 056 000000 N 057 000000 N 058 A000000 N 059 000000 Y 060 A000000 N 060 B000000 N 061 000000 0 062 A000000 Y 062 B000000 0.0 062 C000000 0.0 062 D000000 3.0 062 E000000 0.0 062 F000000 0.0 062 G000000 0.0 062 H000000 0.0 062 I000000 0.0 062 J000000 1.4 062 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 169.7 062 R000000 2.4 063 A000000 0 063 B000000 4.8 064 A000000 Y 064 B000000 Y 065 000000 Y 066 A000000 N 067 000000 N 068 A000000 N 068 B000000 N PAGE 8 069 000000 N 070 A010000 Y 070 A020000 Y 070 B010000 N 070 B020000 N 070 C010000 Y 070 C020000 N 070 D010000 N 070 D020000 N 070 E010000 Y 070 E020000 N 070 F010000 N 070 F020000 N 070 G010000 Y 070 G020000 N 070 H010000 N 070 H020000 N 070 I010000 N 070 I020000 N 070 J010000 Y 070 J020000 Y 070 K010000 Y 070 K020000 N 070 L010000 Y 070 L020000 Y 070 M010000 Y 070 M020000 N 070 N010000 Y 070 N020000 N 070 O010000 Y 070 O020000 Y 070 P010000 Y 070 P020000 Y 070 Q010000 N 070 Q020000 N 070 R010000 N 070 R020000 N 071 A000000 2571311 071 B000000 1890374 071 C000000 2249050 071 D000000 84 072 A000000 12 072 B000000 105424 072 C000000 96 072 D000000 0 072 E000000 5145 072 F000000 19021 072 G000000 4475 072 H000000 0 072 I000000 35 072 J000000 588 PAGE 9 072 K000000 0 072 L000000 553 072 M000000 105 072 N000000 117 072 O000000 0 072 P000000 4719 072 Q000000 227 072 R000000 73 072 S000000 960 072 T000000 0 072 U000000 0 072 V000000 0 072 W000000 2924 072 X000000 33797 072 Y000000 0 072 Z000000 76868 072AA000000 21290 072BB000000 0 072CC010000 79994 072CC020000 0 072DD010000 71824 072DD020000 0 072EE000000 0 073 A010000 0.4000 073 A020000 0.0000 073 B000000 0.0000 073 C000000 0.0000 074 A000000 0 074 B000000 47200 074 C000000 21731 074 D000000 0 074 E000000 1073 074 F000000 36481 074 G000000 0 074 H000000 0 074 I000000 2637505 074 J000000 5216 074 K000000 0 074 L000000 9467 074 M000000 164 074 N000000 2758837 074 O000000 50430 074 P000000 2689 074 Q000000 450000 074 R010000 0 074 R020000 0 074 R030000 0 074 R040000 1479 074 S000000 700130 074 T000000 1554109 074 U010000 180010 PAGE 10 074 U020000 0 074 V010000 8.63 074 V020000 0.00 074 W000000 0.0000 074 X000000 831 074 Y000000 0 075 A000000 0 075 B000000 2237750 076 000000 8.84 077 A000000 Y 077 B000000 Y 077 C000000 N 077 D000000 Y 077 E000000 N 077 F000000 N 077 G000000 N 077 H000000 N 077 I000000 N 077 J000000 N 077 K000000 N 077 L000000 N 077 M000000 N 077 N000000 N 077 O000000 N 077 P000000 N 077 Q010000 N 077 Q020000 N 077 Q030000 N 078 000000 N 080 A000000 ICI MUTAL INSURANCE COMPANY 080 C000000 85000 081 A000000 Y 081 B000000 96 082 A000000 Y 082 B000000 100 083 A000000 N 083 B000000 0 084 A000000 N 084 B000000 0 085 A000000 Y 085 B000000 N 086 A010000 0 086 A020000 0 086 B010000 0 086 B020000 0 086 C010000 0 086 C020000 0 086 D010000 0 086 D020000 0 086 E010000 0 086 E020000 0 PAGE 11 086 F010000 0 086 F020000 0 087 A010000 COMMON 087 A020000 920961109 087 A030000 VVR 088 A000000 N 088 B000000 N 088 C000000 N 088 D000000 Y SIGNATURE KATHERINE UREVIG TITLE ASSISTANT TREASURER