PAGE 1 000 A000000 02/28/2007 000 C000000 0001181187 000 D000000 N 000 E000000 NF 000 F000000 Y 000 G000000 N 000 H000000 N 000 I000000 6.1 000 J000000 A 001 A000000 BLACKROCK INSURED MUNICIPAL INCOME TRUST 001 B000000 811-21178 001 C000000 8888252257 002 A000000 100 BELLEVUE PARKWAY 002 B000000 WILMINGTON 002 C000000 DE 002 D010000 19809 003 000000 N 004 000000 N 005 000000 N 006 000000 N 007 A000000 N 007 B000000 0 007 C010100 1 008 A000001 BLACKROCK ADVISORS, LLC 008 B000001 A 008 C000001 801-47710 008 D010001 WILMINGTON 008 D020001 DE 008 D030001 19809 008 A000002 BLACKROCK FINANCIAL MANAGEMENT,INC. 008 B000002 S 008 C000002 801-48433 008 D010002 NEW YORK 008 D020002 NY 008 D030002 10022 012 A000001 COMPUTERSHARE TRUST COMPANY, NA 012 B000001 85-11340 012 C010001 CANTON 012 C020001 MA 012 C030001 02021 013 A000001 DELOITTE & TOUCHE LLP 013 B010001 BOSTON 013 B020001 MA 013 B030001 02116 014 A000001 BLACKROCK INVESTMENTS, INC. 014 B000001 8-048436 014 A000002 NORTHERN FUND DISTRIBUTORS, LLC 014 B000002 8-051242 014 A000003 PNC CAPITAL MARKETS, INC. 014 B000003 8-032493 014 A000004 J.J.B. HILLIARD W.L. LYONS, INC. PAGE 2 014 B000004 8-033133 014 A000005 PFPC DISTRIBUTORS, INC. 014 B000005 8-045467 014 A000006 MGI FUNDS DISTRIBUTOR, INC. 014 B000006 8-046960 014 A000007 ABN AMRO DISTRIBUTION SERVICES (USA), INC. 014 B000007 8-052396 014 A000008 BLACKROCK DISTRIBUTORS, INC. 014 B000008 8-048775 014 A000009 PERSIMMON SECURITIES 014 B000009 8-053071 014 A000010 PNC INVESTMENTS LLC 014 B000010 8-066195 014 A000011 MLPF&S AND OTHER ML BROKER/DEALER AFFILIATES 014 B000011 8-7221 014 A000012 Harris Williams LLC 014 B000012 8-53380 014 A000013 Mercantile Brokerage Services, Inc. 014 B000013 8-18210 014 A000014 Northern Trust Securities, Inc. 014 B000014 8-23689 014 A000015 PNC Brokerage Corp. 014 B000015 8-46315 015 A000001 STATESTREET BANK AND TRUST COMPANY 015 B000001 C 015 C010001 BOSTON 015 C020001 MA 015 C030001 02110 015 E010001 X 015 A000002 PRUDENTIAL SECURITIES, INC. 015 B000002 C 015 C010002 SPRING LAKE 015 C020002 NJ 015 C030002 07762 015 C040002 1443 015 E020002 X 018 000000 Y 019 A000000 Y 019 B000000 57 019 C000000 BLACKROCKF 020 A000001 MERRILL LYNCH 020 B000001 13-5674085 020 C000001 10 021 000000 10 022 A000001 STATE STREET BANK 022 B000001 04-1867445 022 C000001 131800 022 D000001 131150 022 A000002 CITIGROUP 022 B000002 11-2418191 022 C000002 51558 PAGE 3 022 D000002 66981 022 A000003 MORGAN STANLEY 022 B000003 13-2655998 022 C000003 17680 022 D000003 26426 022 A000004 GOLDMAN SACHS & CO. 022 B000004 13-5108880 022 C000004 26274 022 D000004 15733 022 A000005 MERRILL LYNCH 022 B000005 13-5674085 022 C000005 11644 022 D000005 12062 022 A000006 UBS SECURITIES 022 B000006 13-2932996 022 C000006 19781 022 D000006 1901 022 A000007 LEHMAN BROTHERS 022 B000007 13-2518466 022 C000007 0 022 D000007 19030 022 A000008 CHASE SECURITIES, INC. 022 B000008 13-3379014 022 C000008 15592 022 D000008 2243 022 A000009 BEAR STEARNS & CO. 022 B000009 13-3299429 022 C000009 5591 022 D000009 11405 022 A000010 BANC OF AMERICA 022 B000010 56-2058405 022 C000010 6028 022 D000010 2000 023 C000000 285948 023 D000000 295992 024 000000 N 026 A000000 N 026 B000000 N 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 0 028 B010000 0 PAGE 4 028 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 0.550 048 A010000 0 048 A020000 0.000 048 B010000 0 PAGE 5 048 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 Y 053 B000000 Y 053 C000000 N 054 A000000 Y 054 B000000 Y 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 N 055 A000000 Y 055 B000000 N 056 000000 Y 057 000000 N 058 A000000 N 059 000000 Y 060 A000000 Y 060 B000000 Y 061 000000 0 062 A000000 Y PAGE 6 062 B000000 0.0 062 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 1.5 062 M000000 0.0 062 N000000 0.0 062 O000000 153.6 062 P000000 0.0 062 Q000000 0.0 062 R000000 0.0 063 A000000 0 063 B000000 36.2 064 A000000 Y 064 B000000 N 066 A000000 N 067 000000 N 068 A000000 N 068 B000000 N 069 000000 N 070 A010000 Y 070 A020000 N 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 N 070 K010000 Y 070 K020000 Y 070 L010000 N 070 L020000 N 070 M010000 N PAGE 7 070 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 Y 070 R020000 N 071 A000000 64564 071 B000000 40574 071 C000000 618648 071 D000000 7 072 A000000 6 072 B000000 15138 072 C000000 0 072 D000000 0 072 E000000 2 072 F000000 1743 072 G000000 0 072 H000000 0 072 I000000 7 072 J000000 40 072 K000000 0 072 L000000 46 072 M000000 16 072 N000000 11 072 O000000 0 072 P000000 1 072 Q000000 0 072 R000000 20 072 S000000 37 072 T000000 0 072 U000000 0 072 V000000 0 072 W000000 345 072 X000000 2267 072 Y000000 634 072 Z000000 13507 072AA000000 0 072BB000000 2244 072CC010000 9948 072CC020000 0 072DD010000 9591 072DD020000 0 072EE000000 1350 073 A010000 0.3660 073 A020000 0.0000 073 B000000 0.0515 PAGE 8 073 C000000 0.0000 074 A000000 1 074 B000000 0 074 C000000 0 074 D000000 635412 074 E000000 0 074 F000000 0 074 G000000 0 074 H000000 0 074 I000000 6300 074 J000000 4834 074 K000000 0 074 L000000 6640 074 M000000 118 074 N000000 653305 074 O000000 6817 074 P000000 206 074 Q000000 0 074 R010000 0 074 R020000 0 074 R030000 0 074 R040000 3445 074 S000000 229050 074 T000000 413787 074 U010000 26204 074 U020000 0 074 V010000 15.79 074 V020000 0.00 074 W000000 0.0000 074 X000000 129 074 Y000000 0 075 A000000 0 075 B000000 410264 076 000000 15.06 077 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 0 086 D020000 0 086 E010000 0 086 E020000 0 PAGE 9 086 F010000 0 086 F020000 0 087 A010000 COMMON 087 A020000 092479104 087 A030000 BYM 088 A000000 N 088 B000000 N 088 C000000 N 088 D000000 Y SIGNATURE DONALD C. BURKE TITLE TREASURER