PAGE 1
000 B000000 04/30/2013
000 C000000 0000901243
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 MUNIASSETS FUND, INC.
001 B000000 811-07642
001 C000000 8004417762
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 INVESTMENT MANAGEMENT, LLC
008 B000002 S
008 C000002 801-56972
008 D010002 PRINCETON
008 D020002 NJ
008 D030002 08540
012 A000001 COMPUTERSHARE TRUST COMPANY, N.A.
012 B000001 85-11340
012 C010001 CANTON
012 C020001 MA
012 C030001 02021
012 A000002 THE BANK OF NEW YORK MELLON (PREFERRED)
012 B000002 85-05006
012 C010002 NEW YORK
012 C020002 NY
012 C030002 10289
013 A000001 DELOITTE & TOUCHE LLP
013 B010001 BOSTON
013 B020001 MA
013 B030001 02116
014 A000001 BLACKROCK CAPITAL MARKETS, LLC
014 B000001 8-67827
PAGE 2
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 THE BANK OF NEW YORK MELLON
015 B000001 C
015 C010001 NEW YORK
015 C020001 NY
015 C030001 10286
015 E010001 X
015 A000002 JPMORGAN CHASE BANK, N.A.
015 B000002 S
015 C010002 NEW YORK
015 C020002 NY
015 C030002 10017
018 000000 Y
019 A000000 Y
019 B000000 290
019 C000000 BLKRKADVSR
020 A000001 BANK OF AMERICA CORP
020 B000001 56-0906609
020 C000001 1
021 000000 1
022 A000001 FFI INSTITUTIONAL TAX-EXEMPT FUND
022 B000001 22-2509978
022 C000001 66374
022 D000001 60570
022 A000002 CITIGROUP GLOBAL MARKETS, INC.
022 B000002 11-2418191
022 C000002 22173
022 D000002 16394
022 A000003 BARCLAYS CAPITAL INC.
022 B000003 06-1031656
022 C000003 25302
022 D000003 7521
022 A000004 BANK OF AMERICA CORP
022 B000004 56-0906609
022 C000004 13182
022 D000004 10685
022 A000005 J.P. MORGAN SECURITIES INC
022 B000005 13-3379014
022 C000005 9617
022 D000005 7167
022 A000006 GOLDMAN SACHS & CO
022 B000006 13-5108880
PAGE 3
022 C000006 10505
022 D000006 3324
022 A000007 JEFFERIES & COMPANY INC
022 B000007 95-2622900
022 C000007 7766
022 D000007 4684
022 A000008 MORGAN STANLEY
022 B000008 36-3145972
022 C000008 5245
022 D000008 3721
022 A000009 BB&T CORP
022 B000009 56-0939887
022 C000009 6793
022 D000009 1149
022 A000010 MESIROW FINANCIAL, INC.
022 B000010 36-3194849
022 C000010 3013
022 D000010 4763
023 C000000 186521
023 D000000 138468
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
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
PAGE 4
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
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
PAGE 5
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 N
054 H000000 Y
054 I000000 N
054 J000000 Y
054 K000000 N
054 L000000 N
054 M000000 Y
054 N000000 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 1.8
062 M000000 0.0
062 N000000 0.0
062 O000000 112.2
062 P000000 0.0
062 Q000000 0.0
PAGE 6
062 R000000 0.0
063 A000000 0
063 B000000 22.8
064 A000000 Y
064 B000000 Y
065 000000 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 Y
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
070 M020000 N
070 N010000 N
070 N020000 N
070 O010000 Y
070 O020000 N
070 P010000 Y
070 P020000 Y
070 Q010000 N
070 Q020000 N
070 R010000 N
070 R020000 N
071 A000000 120147
071 B000000 107812
071 C000000 559650
071 D000000 19
PAGE 7
072 A000000 12
072 B000000 31819
072 C000000 0
072 D000000 0
072 E000000 0
072 F000000 3120
072 G000000 105
072 H000000 0
072 I000000 59
072 J000000 27
072 K000000 0
072 L000000 22
072 M000000 52
072 N000000 20
072 O000000 0
072 P000000 597
072 Q000000 0
072 R000000 83
072 S000000 42
072 T000000 0
072 U000000 0
072 V000000 0
072 W000000 20
072 X000000 4147
072 Y000000 1
072 Z000000 27673
072AA000000 4182
072BB000000 0
072CC010000 27646
072CC020000 0
072DD010000 27772
072DD020000 0
072EE000000 0
073 A010000 0.7767
073 A020000 0.0000
073 B000000 0.0000
073 C000000 0.0000
074 A000000 242
074 B000000 0
074 C000000 0
074 D000000 576744
074 E000000 0
074 F000000 0
074 G000000 0
074 H000000 0
074 I000000 9209
074 J000000 7002
074 K000000 0
074 L000000 9300
074 M000000 9
074 N000000 602506
PAGE 8
074 O000000 9231
074 P000000 265
074 Q000000 0
074 R010000 0
074 R020000 0
074 R030000 0
074 R040000 79087
074 S000000 0
074 T000000 513923
074 U010000 35784
074 U020000 0
074 V010000 14.36
074 V020000 0.00
074 W000000 0.0000
074 X000000 15502
074 Y000000 27195
075 A000000 0
075 B000000 501763
076 000000 13.96
077 A000000 Y
077 B000000 Y
077 O000000 Y
078 000000 N
080 A000000 FEDERAL INSURANCE COMPANY
080 B000000 NAT UNION FIRE INS CO OF PITTSBURGH, PA
080 C000000 72025
081 A000000 Y
081 B000000 90
082 A000000 N
082 B000000 0
083 A000000 N
083 B000000 0
084 A000000 N
084 B000000 0
085 A000000 Y
085 B000000 N
086 A010000 42
086 A020000 597
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 09254J102
087 A030000 MUA
PAGE 9
088 A000000 N
088 B000000 N
088 C000000 N
088 D000000 N
SIGNATURE NEAL J. ANDREWS
TITLE CFO