PAGE 1
000 A000000 04/30/2013
000 C000000 0001562818
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 MULTI SECTOR INCOME TRUST
001 B000000 811-22774
001 C000000 8002217210
002 A000000 100 BELLEVUE PARKWAY
002 B000000 WILMINGTON
002 C000000 DE
002 D010000 19809
003 000000 Y
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 INVESTMENT MANAGEMENT, LLC
008 B000002 S
008 C000002 801-56972
008 D010002 PRINCETON
008 D020002 NJ
008 D030002 08540
008 A000003 BLACKROCK FINANCIAL MANAGEMENT, INC.
008 B000003 S
008 C000003 801-48433
008 D010003 NEW YORK
008 D020003 NY
008 D030003 10055
008 A000004 BLACKROCK SINGAPORE LIMITED
008 B000004 S
008 C000004 801-76926
008 D010004 SINGAPORE
008 D050004 SINGAPORE
012 A000001 COMPUTERSHARE TRUST COMPANY, N.A. (COMMON)
012 B000001 85-11340
012 C010001 CANTON
012 C020001 MA
012 C030001 02021
PAGE 2
013 A000001 DELOITTE & TOUCHE LLP
013 B010001 BOSTON
013 B020001 MA
013 B030001 02116
014 A000001 BLACKROCK CAPITAL MARKETS, LLC
014 B000001 8-67827
014 A000002 BLACKROCK EXECUTION SERVICES
014 B000002 8-48719
014 A000003 BLACKROCK INVESTMENTS, LLC
014 B000003 8-48436
014 A000004 HARRIS WILLIAMS LLC
014 B000004 8-53380
014 A000005 PNC CAPITAL MARKETS, INC.
014 B000005 8-32493
014 A000006 PNC INVESTMENTS LLC
014 B000006 8-66195
015 A000001 STATE STREET BANK & TRUST COMPANY
015 B000001 C
015 C010001 BOSTON
015 C020001 MA
015 C030001 02110
015 E010001 X
015 A000002 BANK OF NEW YORK MELLON
015 B000002 S
015 C010002 NEW YORK
015 C020002 NY
015 C030002 10286
015 E010002 X
015 A000003 J.P. MORGAN CHASE BANK
015 B000003 S
015 C010003 NEW YORK
015 C020003 NY
015 C030003 10017
015 E010003 X
015 A000004 CITIBANK N.A.
015 B000004 S
015 C010004 BUENOS AIRES
015 D010004 ARGENTINA
015 E040004 X
015 A000005 HSBC AUSTRALIA
015 B000005 S
015 C010005 SYDNEY
015 D010005 AUSTRALIA
015 D020005 NSW2000
015 E040005 X
015 A000006 STATE STREET TRUST COMPANY CANADA
015 B000006 S
015 C010006 TORONTO
015 D010006 CANADA
015 D020006 M5V 3L3
015 E040006 X
PAGE 3
015 A000007 CLEARSTREAM BANKING SA
015 B000007 S
015 C010007 LUXEMBOURG
015 D010007 LUXEMBOURG
015 E040007 X
015 A000008 DEUTSCHE BANK
015 B000008 S
015 C010008 MILAN
015 D010008 ITALY
015 D020008 20124
015 E040008 X
015 A000009 BANCO NACIONAL DE MEXICO SA
015 B000009 S
015 C010009 MEXICO CITY
015 D010009 MEXICO
015 D020009 01210
015 E040009 X
015 A000010 HSBC NEW ZEALAND
015 B000010 S
015 C010010 AUCKLAND
015 D010010 NEW ZEALAND
015 E040010 X
015 A000011 SEB NORWAY
015 B000011 S
015 C010011 OSLO
015 D010011 NORWAY
015 D020011 NO-0123
015 E040011 X
015 A000012 STATE STREET BANK
015 B000012 S
015 C010012 LONDON
015 D010012 UNITED KINGDOM
015 E040012 X
018 000000 Y
019 A000000 Y
019 B000000 290
019 C000000 BLKRKADVSR
020 A000001 UBS SECURITIES LLC
020 B000001 13-3873456
020 C000001 1
021 000000 1
022 A000001 BLK LIQUIDITY FUNDS, TEMPFUND, INST. CLASS
022 B000001 52-0983343
022 C000001 786117
022 D000001 774002
022 A000002 DEUTSCHE BANK SECURITIES INC
022 B000002 13-2730828
022 C000002 93711
022 D000002 168169
022 A000003 BARCLAYS CAPITAL INC.
022 B000003 06-1031656
PAGE 4
022 C000003 124967
022 D000003 36139
022 A000004 BANK OF AMERICA CORP
022 B000004 56-0906609
022 C000004 107392
022 D000004 32437
022 A000005 J.P. MORGAN SECURITIES INC
022 B000005 13-3379014
022 C000005 114809
022 D000005 19189
022 A000006 CREDIT SUISSE
022 B000006 13-3442768
022 C000006 105300
022 D000006 6124
022 A000007 UBS SECURITIES LLC
022 B000007 13-3873456
022 C000007 14838
022 D000007 80805
022 A000008 GOLDMAN SACHS & CO
022 B000008 13-5108880
022 C000008 88083
022 D000008 0
022 A000009 MORGAN STANLEY
022 B000009 36-3145972
022 C000009 77638
022 D000009 165
022 A000010 CITIGROUP GLOBAL MARKETS INC
022 B000010 11-2418191
022 C000010 75974
022 D000010 0
023 C000000 1853987
023 D000000 1125859
024 000000 Y
025 A000001 MORGAN STANLEY
025 B000001 36-3145972
025 C000001 D
025 D000001 27921
025 A000002 CITIGROUP GLOBAL MARKETS INC
025 B000002 11-2418191
025 C000002 D
025 D000002 16400
025 A000003 J.P. MORGAN SECURITIES INC
025 B000003 13-3379014
025 C000003 D
025 D000003 11797
025 A000004 UBS SECURITIES LLC
025 B000004 13-3873456
025 C000004 D
025 D000004 10527
025 A000005 BANK OF AMERICA CORP
025 B000005 56-0906609
PAGE 5
025 C000005 D
025 D000005 5399
025 A000006 GOLDMAN SACHS & CO
025 B000006 13-5108880
025 C000006 E
025 D000006 4114
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
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
PAGE 6
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 0.800
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 Y
053 B000000 Y
053 C000000 N
054 A000000 Y
054 B000000 Y
054 C000000 N
054 D000000 N
PAGE 7
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 N
056 000000 Y
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 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 1.6
062 M000000 0.0
062 N000000 4.7
062 O000000 0.0
062 P000000 53.7
062 Q000000 75.2
062 R000000 2.9
063 A000000 0
063 B000000 23.4
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 N
070 B010000 Y
070 B020000 N
PAGE 8
070 C010000 Y
070 C020000 N
070 D010000 Y
070 D020000 N
070 E010000 Y
070 E020000 Y
070 F010000 Y
070 F020000 N
070 G010000 Y
070 G020000 N
070 H010000 Y
070 H020000 N
070 I010000 N
070 I020000 N
070 J010000 Y
070 J020000 N
070 K010000 Y
070 K020000 Y
070 L010000 Y
070 L020000 Y
070 M010000 Y
070 M020000 Y
070 N010000 Y
070 N020000 N
070 O010000 Y
070 O020000 Y
070 P010000 Y
070 P020000 N
070 Q010000 N
070 Q020000 N
070 R010000 Y
070 R020000 Y
071 A000000 1182331
071 B000000 177126
071 C000000 687539
071 D000000 26
072 A000000 2
072 B000000 7210
072 C000000 24
072 D000000 0
072 E000000 0
072 F000000 1048
072 G000000 24
072 H000000 0
072 I000000 15
072 J000000 17
072 K000000 0
072 L000000 6
072 M000000 14
072 N000000 3
072 O000000 0
PAGE 9
072 P000000 67
072 Q000000 0
072 R000000 22
072 S000000 14
072 T000000 0
072 U000000 0
072 V000000 0
072 W000000 43
072 X000000 1273
072 Y000000 19
072 Z000000 5980
072AA000000 0
072BB000000 241
072CC010000 16985
072CC020000 0
072DD010000 4484
072DD020000 0
072EE000000 0
073 A010000 0.1167
073 A020000 0.0000
073 B000000 0.0000
073 C000000 0.0000
074 A000000 1164
074 B000000 0
074 C000000 0
074 D000000 1002869
074 E000000 21941
074 F000000 0
074 G000000 0
074 H000000 0
074 I000000 12675
074 J000000 3759
074 K000000 0
074 L000000 10458
074 M000000 0
074 N000000 1052866
074 O000000 76816
074 P000000 565
074 Q000000 0
074 R010000 220742
074 R020000 0
074 R030000 0
074 R040000 4154
074 S000000 0
074 T000000 750589
074 U010000 38422
074 U020000 0
074 V010000 19.54
074 V020000 0.00
074 W000000 0.0000
074 X000000 18296
PAGE 10
074 Y000000 71115
075 A000000 0
075 B000000 701289
076 000000 19.16
077 A000000 Y
077 O000000 Y
077 Q010000 Y
078 000000 N
080 C000000 0
081 B000000 0
082 B000000 0
083 B000000 0
084 B000000 0
086 A010000 38421
086 A020000 732349
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
086 F020000 0
087 A010000 COMMON STOCK
087 A020000 09258A107
087 A030000 BIT
088 A000000 N
088 B000000 N
088 C000000 N
088 D000000 N
SIGNATURE NEAL J. ANDREWS
TITLE CFO