PAGE 1
000 B000000 10/31/2011
000 C000000 0001266585
000 D000000 N
000 E000000 NF
000 F000000 Y
000 G000000 N
000 H000000 N
000 I000000 6.1
000 J000000 A
001 A000000 NUVEEN MUNICIPAL HIGH INCOME OPPORTUNITY FUND
001 B000000 811-21449
001 C000000 3129178200
002 A000000 333 WEST WACKER DRIVE
002 B000000 CHICAGO
002 C000000 IL
002 D010000 60606
002 D020000 1286
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 NUVEEN FUND ADVISORS, INC.
008 B000001 A
008 C000001 801-14147
008 D010001 CHICAGO
008 D020001 IL
008 D030001 60606
008 D040001 1286
008 A000002 NUVEEN ASSET MANAGEMENT, LLC
008 B000002 S
008 C000002 801-71957
008 D010002 CHICAGO
008 D020002 IL
008 D030002 60606
008 D040002 1286
012 A000001 EQUISERVE INC.
012 B000001 84-05925
012 C010001 PROVIDENCE
012 C020001 RI
PAGE 2
012 C030001 02940
013 A000001 ERNST & YOUNG LLP
013 B010001 CHICAGO
013 B020001 IL
013 B030001 60606
014 A000001 NUVEEN INVESTMENTS, LLC
014 B000001 8-13464
015 A000001 STATE STREET BANK AND TRUST COMPANY
015 B000001 C
015 C010001 BOSTON
015 C020001 MA
015 C030001 02110
015 E010001 X
018 000000 Y
019 A000000 Y
019 B000000 241
019 C000000 NUVEENFUND
020 C000001 0
020 C000002 0
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 0
022 A000001 FMS BONDS INC
022 B000001 59-1842344
022 C000001 32009
022 D000001 31800
022 A000002 CITIGROUP
022 B000002 13-3214963
022 C000002 14602
022 D000002 48309
022 A000003 MORGAN STANLEY
022 B000003 13-2655998
022 C000003 13572
022 D000003 25882
022 A000004 JP MORGAN CHASE
022 B000004 13-3224016
022 C000004 21569
022 D000004 16997
022 A000005 MERRILL LYNCH
022 B000005 13-5674085
022 C000005 10153
022 D000005 15978
022 A000006 D.A. DAVIDSON
022 B000006 81-0139474
022 C000006 5084
PAGE 3
022 D000006 4917
022 A000007 LOOP CAPITAL MKTS LLC
022 B000007 36-4164012
022 C000007 0
022 D000007 6996
022 A000008 BARCLAYS BANK PLC
022 B000008 13-4942190
022 C000008 3289
022 D000008 2038
022 A000009 GOLDMAN SACHS
022 B000009 13-5108880
022 C000009 3200
022 D000009 1547
022 A000010 ZIEGLER SECURITIES
022 B000010 39-0727640
022 C000010 3135
022 D000010 1474
023 C000000 127460
023 D000000 163593
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 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
PAGE 4
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 N
048 000000 0.000
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
PAGE 5
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 Y
053 A000000 Y
053 B000000 Y
053 C000000 N
054 A000000 Y
054 B000000 N
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
054 O000000 Y
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 0.0
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
PAGE 6
062 J000000 0.0
062 K000000 0.0
062 L000000 0.0
062 M000000 0.0
062 N000000 0.0
062 O000000 119.2
062 P000000 0.0
062 Q000000 0.0
062 R000000 0.0
063 A000000 0
063 B000000 15.3
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 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 N
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 N
070 P020000 N
PAGE 7
070 Q010000 N
070 Q020000 N
070 R010000 N
070 R020000 N
071 A000000 125047
071 B000000 150915
071 C000000 389862
071 D000000 32
072 A000000 12
072 B000000 30524
072 C000000 0
072 D000000 0
072 E000000 0
072 F000000 2927
072 G000000 0
072 H000000 0
072 I000000 2
072 J000000 76
072 K000000 43
072 L000000 87
072 M000000 11
072 N000000 0
072 O000000 0
072 P000000 444
072 Q000000 0
072 R000000 38
072 S000000 843
072 T000000 0
072 U000000 0
072 V000000 0
072 W000000 129
072 X000000 4600
072 Y000000 354
072 Z000000 26278
072AA000000 1196
072BB000000 0
072CC010000 0
072CC020000 14899
072DD010000 26440
072DD020000 0
072EE000000 0
073 A010000 0.9645
073 A020000 0.0000
073 B000000 0.0000
073 C000000 0.0000
074 A000000 0
074 B000000 0
074 C000000 0
074 D000000 385069
074 E000000 0
074 F000000 0
PAGE 8
074 G000000 0
074 H000000 0
074 I000000 0
074 J000000 697
074 K000000 0
074 L000000 10597
074 M000000 147
074 N000000 396510
074 O000000 390
074 P000000 247
074 Q000000 0
074 R010000 0
074 R020000 0
074 R030000 0
074 R040000 72783
074 S000000 0
074 T000000 323090
074 U010000 27872
074 U020000 0
074 V010000 11.59
074 V020000 0.00
074 W000000 0.0000
074 X000000 72
074 Y000000 502376
075 A000000 0
075 B000000 303320
076 000000 11.75
077 A000000 Y
077 B000000 Y
077 E000000 Y
078 000000 N
080 A000000 CHUBB GROUP OF INSURANCE COMPANIES
080 B000000 BERKLEY, GREAT AMERICAN, ST.PAUL,CNA & ZURICH
080 C000000 114000
081 A000000 Y
081 B000000 240
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 0
086 A020000 0
086 B010000 1126
086 B020000 12740
086 C010000 0
086 C020000 0
086 D010000 4
PAGE 9
086 D020000 95000
086 E010000 0
086 E020000 0
086 F010000 0
086 F020000 0
087 A010000 COMMON STOCK
087 A020000 670682103
087 A030000 NMZ
088 A000000 N
088 B000000 N
088 C000000 N
088 D000000 Y
SIGNATURE STEPHEN D. FOY
TITLE V.P. & CONTROLLER