PAGE 1 000 A000000 04/30/2004 000 C000000 0001160864 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 CORE BOND TRUST 001 B000000 811-10543 001 C000000 3027972162 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 1 007 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 10 008 A000001 BLACKROCK ADVISORS, INC. 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 EQUISERVE TRUST COMPANY, NA 012 B000001 85-11340 012 C010001 CANTON 012 C020001 MA 012 C030001 02021 013 A000001 DELOITTE & TOUCHE LLP 013 B010001 BOSTON PAGE 2 013 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. 014 B000004 8-033133 014 A000005 PFPC DISTRIBUTORS, INC. 014 B000005 8-045467 014 A000006 OFFIT 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 015 A000001 STATESTREET BANK AND TRUST COMPANY 015 B000001 C 015 C010001 BOSTON 015 C020001 MA 015 C030001 02171 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 50 019 C000000 BLACKROCKF 020 A000001 CITIGROUP GLOBAL MARKETS INC. 020 B000001 11-2418191 020 C000001 3 020 A000002 CITICORP SECURITIES INC. 020 B000002 13-3082694 020 C000002 3 020 C000003 0 020 C000004 0 020 C000005 0 020 C000006 0 020 C000007 0 020 C000008 0 020 C000009 0 020 C000010 0 021 000000 6 022 A000001 LEHMAN BROTHERS INC. PAGE 3 022 B000001 13-2518466 022 C000001 1258456 022 D000001 418817 022 A000002 CITIGROUP GLOBAL MARKETS INC. 022 B000002 11-2418191 022 C000002 300441 022 D000002 64204 022 A000003 GOLDMAN SACHS 022 B000003 13-5108880 022 C000003 126538 022 D000003 104752 022 A000004 CREDIT SUISSE FIRST BOSTON CORP. 022 B000004 13-5659485 022 C000004 111299 022 D000004 123167 022 A000005 DEUTSCHE BANK SEC. 022 B000005 13-2730828 022 C000005 128289 022 D000005 83453 022 A000006 MORGAN STANLEY CO. INC. 022 B000006 13-2655998 022 C000006 123649 022 D000006 113218 022 A000007 CHASE SEC INC 022 B000007 13-3379014 022 C000007 71158 022 D000007 72803 022 A000008 MERRIL LYNCH & CO., INC. 022 B000008 13-5674085 022 C000008 69579 022 D000008 49271 022 A000009 UBS SECURITIES LLC 022 B000009 13-3873456 022 C000009 49979 022 D000009 29840 022 A000010 BARCLAYS CAPITAL INC. 022 B000010 06-1031656 022 C000010 60016 022 D000010 10049 023 C000000 2529532 023 D000000 1217019 024 000000 Y 025 A000001 GOLDMAN SACHS 025 B000001 13-5108880 025 C000001 D 025 D000001 1381 025 A000002 CREDIT SUISSE FIRST BOSTON CORP. 025 B000002 13-5659485 025 C000002 D 025 D000002 294 025 A000003 LEHMAN BROTHERS, INC. PAGE 4 025 B000003 13-2518466 025 C000003 D 025 D000003 176 025 A000004 HSBC SECURITIES 025 B000004 13-2650272 025 C000004 D 025 D000004 2084 025 A000005 JP MORGAN CHASE 025 B000005 13-3379014 025 C000005 D 025 D000005 4499 025 A000006 MORGAN STANLEY 025 B000006 13-2655998 025 C000006 D 025 D000006 27113 025 A000007 BANK OF AMERICA SECURITIES LLC 025 B000007 56-2058405 025 C000007 D 025 D000007 3066 025 A000008 BARCLAYS CAPITAL INC. 025 B000008 06-1031656 025 C000008 D 025 D000008 683 025 A000009 CITIGROUP GLOBAL MARKETS INC. 025 B000009 11-2418191 025 C000009 D 025 D000009 5940 025 A000010 WACHOVIA BANK N.A. 025 B000010 34-1542819 025 C000010 D 025 D000010 1261 025 D000011 0 025 D000012 0 025 D000013 0 025 D000014 0 025 D000015 0 025 D000016 0 026 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 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 0.550 048 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 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 062 B000000 0.1 PAGE 7 062 C000000 8.9 062 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 55.8 062 N000000 26.6 062 O000000 0.2 062 P000000 61.1 062 Q000000 11.1 062 R000000 0.0 063 A000000 0 063 B000000 8.8 064 A000000 N 064 B000000 N 066 A000000 N 067 000000 N 068 A000000 N 068 B000000 N 069 000000 N 070 A010000 Y 070 A020000 Y 070 B010000 N 070 B020000 N 070 C010000 Y 070 C020000 Y 070 D010000 N 070 D020000 N 070 E010000 Y 070 E020000 Y 070 F010000 N 070 F020000 N 070 G010000 Y 070 G020000 Y 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 Y PAGE 8 070 N010000 Y 070 N020000 N 070 O010000 Y 070 O020000 N 070 P010000 Y 070 P020000 N 070 Q010000 N 070 Q020000 N 070 R010000 Y 070 R020000 N 071 A000000 1142854 071 B000000 1053696 071 C000000 639532 071 D000000 165 072 A000000 6 072 B000000 16478 072 C000000 0 072 D000000 0 072 E000000 0 072 F000000 1539 072 G000000 0 072 H000000 0 072 I000000 7 072 J000000 77 072 K000000 0 072 L000000 46 072 M000000 29 072 N000000 16 072 O000000 0 072 P000000 646 072 Q000000 0 072 R000000 23 072 S000000 24 072 T000000 0 072 U000000 0 072 V000000 0 072 W000000 41 072 X000000 2448 072 Y000000 0 072 Z000000 14030 072AA000000 4982 072BB000000 0 072CC010000 0 072CC020000 6667 072DD010000 10869 072DD020000 0 072EE000000 4915 073 A010000 0.4023 073 A020000 0.0000 073 B000000 0.1819 073 C000000 0.0000 PAGE 9 074 A000000 193 074 B000000 0 074 C000000 35712 074 D000000 611547 074 E000000 0 074 F000000 0 074 G000000 0 074 H000000 0 074 I000000 0 074 J000000 22622 074 K000000 0 074 L000000 39366 074 M000000 394 074 N000000 709834 074 O000000 164067 074 P000000 232 074 Q000000 0 074 R010000 118009 074 R020000 0 074 R030000 1153 074 R040000 31272 074 S000000 0 074 T000000 395101 074 U010000 27019 074 U020000 0 074 V010000 14.62 074 V020000 0.00 074 W000000 0.0000 074 X000000 89 074 Y000000 121127 075 A000000 0 075 B000000 404739 076 000000 13.09 077 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 0 086 F010000 0 PAGE 10 086 F020000 0 087 A010000 COMMON STOCK 087 A020000 09249E101 087 A030000 BHK 088 A000000 N 088 B000000 N 088 C000000 N 088 D000000 N SIGNATURE HENRY GABBAY TITLE TREASURER