PAGE 1
000 A000000 10/31/2008
000 C000000 0001223026
000 D000000 N
000 E000000 NF
000 F000000 Y
000 G000000 N
000 H000000 N
000 I000000 6.1
000 J000000 A
001 A000000 PIONEER MUNICIPAL HIGH INCOME TRUST
001 B000000 811-21321
001 C000000 6177427825
002 A000000 60 STATE STREET
002 B000000 BOSTON
002 C000000 MA
002 D010000 02109
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 PIONEER INVESTMENT MANAGEMENT, INC.
008 B000001 A
008 C000001 801-8255
008 D010001 BOSTON
008 D020001 MA
008 D030001 02109
010 A000001 PIONEER INVESTMENT MANAGEMENT, INC.
010 B000001 801-8255
010 C010001 BOSTON
010 C020001 MA
010 C030001 02109
010 A000002 PRINCETON ADMINISTRATORS, LLC
010 C010002 PRINCETON
010 C020002 NJ
010 C030002 08543
010 C040002 9095
011 A000001 PIONEER FUNDS DISTRIBUTOR, INC.
011 B000001 8-12345678
011 C010001 BOSTON
PAGE 2
011 C020001 MA
011 C030001 02109
011 A000002 UBS INVESTMENT BANK
011 B000002 8-022651
011 C010002 STAMFORD
011 C020002 CT
011 C030002 06901
011 A000003 RBC CAPITAL MARKETS CORP.
011 B000003 8-045411
011 C010003 MINNEAPOLIS
011 C020003 MN
011 C030003 55402
011 C040003 4422
011 A000004 ADVEST, INC.
011 B000004 8-21409
011 C010004 HARTFORD
011 C020004 CT
011 C030004 06103
011 A000005 JANNEY MONTGOMERY SCOTT, LLC
011 B000005 8-462
011 C010005 PHILADELPHIA
011 C020005 PA
011 C030005 19103
011 C040005 1675
011 A000006 MCDONALD INVESTMENTS, INC.
011 B000006 8-30177
011 C010006 CLEVELAND
011 C020006 OH
011 C030006 44114
011 C040006 2603
011 A000007 STIFEL, NICOLAUS & CO., INC.
011 B000007 8-001447
011 C010007 ST. LOUIS
011 C020007 MO
011 C030007 63102
012 A000001 PIONEER INVEST. MGT. SHAREHOLDER SVCS., INC.
012 B000001 85-01359
012 C010001 BOSTON
012 C020001 MA
012 C030001 02109
012 A000002 AMERICAN STOCK TRANSFER & TRUST CO. (COMMON)
012 B000002 85-00000
012 C010002 BROOKLYN
012 C020002 NY
012 C030002 11219
012 A000003 DEUTSCHE BANK TRUST COMPANY AMERICAS (PREF.)
012 B000003 85-00000
012 C010003 NEW YORK
012 C020003 NY
012 C030003 10005
013 A000001 ERNST & YOUNG LLP
PAGE 3
013 B010001 BOSTON
013 B020001 MA
013 B030001 02116
013 B040001 5072
015 A000001 BROWN BROTHERS HARRIMAN & CO.
015 B000001 C
015 C010001 BOSTON
015 C020001 MA
015 C030001 02109
015 E010001 X
018 000000 Y
019 A000000 Y
019 B000000 76
019 C000000 PIONEERFDS
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 BLACKROCK INVESTMENTS, INC.
022 C000001 19000
022 D000001 0
022 A000002 FIRST TRYON SECURITIES, LLC
022 B000002 56-1986792
022 C000002 0
022 D000002 13888
022 A000003 LEHMAN BROTHERS, INC.
022 B000003 13-2518466
022 C000003 9744
022 D000003 985
022 A000004 B.C. ZIEGLER AND CO.
022 B000004 39-0727640
022 C000004 6500
022 D000004 0
022 A000005 SOUTHRIDGE INVESTMENT GROUP
022 C000005 0
022 D000005 4744
022 A000006 PIPER JAFFRAY & CO.
022 B000006 41-0953246
022 C000006 0
022 D000006 4717
022 A000007 BARCLAYS CAPITAL, INC.
022 C000007 0
022 D000007 4069
022 A000008 DEPFA FIRST ALBANY SECURITIES, LLC
PAGE 4
022 B000008 43-2117279
022 C000008 2500
022 D000008 0
022 A000009 OPPENHEIMER & CO., INC.
022 C000009 2429
022 D000009 0
022 A000010 CITIGROUP GLOBAL MARKETS, INC.
022 B000010 11-2418191
022 C000010 1245
022 D000010 0
023 C000000 42388
023 D000000 28403
024 000000 N
026 A000000 N
026 B000000 Y
026 C000000 N
026 D000000 Y
026 E000000 N
026 F000000 N
026 G010000 N
026 G020000 N
026 H000000 N
027 000000 N
045 000000 Y
046 000000 N
047 000000 Y
048 000000 0.600
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
PAGE 5
051 000000 N
052 000000 N
053 A000000 N
054 A000000 Y
054 B000000 Y
054 C000000 Y
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 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 0.0
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 0.0
062 M000000 0.0
062 N000000 0.0
062 O000000 135.5
062 P000000 0.0
062 Q000000 3.8
062 R000000 1.1
063 A000000 0
063 B000000 20.5
064 A000000 Y
064 B000000 Y
065 000000 N
066 A000000 N
PAGE 6
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 Y
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 N
070 Q010000 N
070 Q020000 N
070 R010000 N
070 R020000 N
071 A000000 38015
071 B000000 37538
071 C000000 384778
071 D000000 10
072 A000000 6
072 B000000 13893
072 C000000 0
072 D000000 0
072 E000000 0
072 F000000 1190
072 G000000 174
PAGE 7
072 H000000 0
072 I000000 154
072 J000000 25
072 K000000 0
072 L000000 12
072 M000000 7
072 N000000 12
072 O000000 0
072 P000000 0
072 Q000000 0
072 R000000 30
072 S000000 21
072 T000000 0
072 U000000 0
072 V000000 0
072 W000000 26
072 X000000 1651
072 Y000000 0
072 Z000000 12242
072AA000000 1554
072BB000000 0
072CC010000 0
072CC020000 74844
072DD010000 9297
072DD020000 0
072EE000000 0
073 A010000 0.4200
073 A020000 0.0000
073 B000000 0.0000
073 C000000 0.0000
074 A000000 0
074 B000000 0
074 C000000 0
074 D000000 333078
074 E000000 0
074 F000000 2717
074 G000000 0
074 H000000 0
074 I000000 0
074 J000000 280
074 K000000 0
074 L000000 8442
074 M000000 30
074 N000000 344547
074 O000000 899
074 P000000 203
074 Q000000 0
074 R010000 0
074 R020000 0
074 R030000 0
074 R040000 3309
PAGE 8
074 S000000 101021
074 T000000 239115
074 U010000 22141
074 U020000 0
074 V010000 10.80
074 V020000 0.00
074 W000000 0.0000
074 X000000 9336
074 Y000000 0
075 A000000 0
075 B000000 292600
076 000000 9.50
077 A000000 N
078 000000 N
080 A000000 ICI MUTUAL INSURANCE CO.
080 C000000 45000
081 A000000 Y
081 B000000 76
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 13
086 A020000 176
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 723763108
087 A030000 MHI
087 B010000 PREFERRED STOCK - SERIES A
087 B020000 723763207
087 C010000 PREFERRED STOCK - SERIES B
087 C020000 723763306
088 A000000 N
088 B000000 N
088 C000000 N
088 D000000 Y
SIGNATURE MARY KELLERMANN
TITLE ACCOUNTING MANAGER