mhisoi.htm
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                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   FORM N-Q

                   CERTIFIED SHAREHOLDER REPORT OF REGISTERED
                        MANAGEMENT INVESTMENT COMPANIES



  Investment Company Act file number 811-21321


                    Pioneer Municipal High Income Trust
               (Exact name of registrant as specified in charter)


                       60 State Street, Boston, MA 02109
              (Address of principal executive offices) (ZIP code)


            Terrence J Cullen, Pioneer Investment Management, Inc.,
                       60 State Street, Boston, MA 02109
                    (Name and address of agent for service)


Registrant's telephone number, including area code:  (617) 742-7825


Date of fiscal year end:  April 30

Date of reporting period:  July 31, 2012

Form N-Q is to be used by management investment companies, other than small
business investment companies registered on Form N-5 (239.24 and 274.5 of this
chapter), to file reports with the Commission, not later than 60 days after
close of the first and third fiscal quarters, pursuant to Rule 30b1-5under
the Investment Company Act of 1940 (17 CFR 270.30b-5).  The Commission may
use the information provided on Form N-Q in its regulatory, disclosure review,
inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-Q,
and the Commission will make this information public. A registrant is not
required to respond to the collection of information contained in Form N-Q
unless the Form displays a currently valid Office of Management and Budget
("OMB") control number. Please direct comments concerning the accuracy of the
information collection burden estimate and any suggestions for reducing the
burden to Secretary, Securities and Exchange Commission, 450 Fifth Street, NW,
Washington, DC 20549-0609.  The OMB has reviewed this collection of information
under the clearance requirements of 44 U.S.C. ss. 3507.


<PAGE>
ITEM 1. Schedule of Investments.






Pioneer Municipal
                     High Income Trust
 NQ| July 31, 2012

 
Ticker Symbols:  MHI
 
 
 
 


 

Schedule of Investments | 7/31/2012 (unaudited)


   
Principal
Amount
USD ($)
S&P/Moody's
Rating
 
Value
 
       
TAX EXEMPT OBLIGATIONS -  123.0% of Net Assets
 
       
Alabama - 2.4%
 
   
  2,500,000 
B-/B2
Alabama Industrial Development Authority Solid Waste Disposal Revenue, 6.45%, 12/1/23   
$ 2,464,250 
   
  1,000,000 
NR/NR
Huntsville-Redstone Village Special Care Facilities Financing Authority, 5.5%, 1/1/28   
  1,011,260 
   
  4,500,000 
NR/NR
Huntsville-Redstone Village Special Care Facilities Financing Authority, 5.5%, 1/1/43   
  4,486,590 
         
$ 7,962,100 
       
Arizona - 0.7%
 
   
  984,000 
NR/Baa3
Pima County Industrial Development Authority, 6.75%, 7/1/31   
$ 986,686 
   
  950,000 
NR/Baa3
Pima County Industrial Development Authority, 7.25%, 7/1/31   
  954,399 
   
  500,000 
NR/Baa2
Yavapai County Industrial Development Authority, 6.0%, 8/1/33   
  522,420 
         
$ 2,463,505 
       
California - 11.8%
 
   
  3,000,000 
NR/A1
Abag Finance Authority for Nonprofit Corp. Revenue, 5.75%, 7/1/37   
$ 3,275,730 
   
  5,100,000 
B-/NR
California County Tobacco Securitization Agency Revenue, 5.125%, 6/1/38   
  4,207,551 
   
  1,000,000 
NR/NR
California Enterprise Development Authority Recovery Zone Facility Revenue, 8.5%, 4/1/31   
  1,157,380 
   
  3,000,000 
BB/NR
California Statewide Communities Development Authority, 7.25%, 10/1/38 (144A) 
  3,189,000 
   
  568,006(a)
NR/NR
California Statewide Communities Development Authority Environmental Facilities Revenue, 9.0%, 12/1/38   
  5,305 
   
  5,150,000(b)
AA+/Aaa
Golden State Tobacco Securitization Corp., 7.8%, 6/1/42   
  5,473,832 
   
  7,000,000(b)
AA+/Aaa
Golden State Tobacco Securitization Corp., 7.875%, 6/1/42   
  7,444,290 
   
  7,885,000(c)
AA-/WR
Lehman Municipal Trust Receipts Revenue, RIB, 10.94%, 9/20/28 (144A) 
  9,925,559 
   
  2,000,000 
B-/Caa1
Tobacco Securitization Authority of Northern California Revenue, 5.375%, 6/1/38   
  1,616,020 
   
  3,000,000 
BB+/B3
Tobacco Securitization Authority of Southern California, 5.0%, 6/1/37   
  2,398,920 
         
$ 38,693,587 
       
Colorado - 1.0%
 
   
  2,000,000 
BBB+/NR
Colorado Health Facilities Authority Revenue, 5.25%, 5/15/42   
$ 2,059,500 
   
  1,000,000 
NR/NR
Kremmling Memorial Hospital District Certificate of Participation, 7.125%, 12/1/45   
  1,116,020 
         
$ 3,175,520 
       
Connecticut - 6.2%
 
   
  1,000,000 
NR/NR
Hamden Connecticut Facility Revenue, 7.75%, 1/1/43   
$ 1,099,690 
   
  10,335,000(d)
AAA/WR
Lehman Municipal Trust Receipts Revenue, 11.665%, 8/21/35   
  14,157,916 
   
  5,000,000 
B/NR
Mohegan Tribe of Indians Gaming Authority, 6.25%, 1/1/31   
  5,002,500 
         
$ 20,260,106 
       
District of Colombia - 3.5%
 
   
  5,000,000 
BBB/Baa1
District of Columbia Tobacco Settlement Financing Corp., 6.5%, 5/15/33   
$ 5,456,050 

   
Principal
Amount
USD ($)
S&P/Moody's
Rating
 
Value
 
       
District of Colombia - (continued)
 
   
  6,000,000 
BBB/Baa1
District of Columbia Tobacco Settlement Financing Corp., 6.75%, 5/15/40   
  6,119,940 
         
$ 11,575,990 
       
Florida - 7.4%
 
   
  1,500,000 
NR/NR
Alachua County Health Facilities Authority Revenue, 8.125%, 11/15/41   
$ 1,731,210 
   
  1,500,000 
NR/NR
Alachua County Health Facilities Authority Revenue, 8.125%, 11/15/46   
  1,725,420 
   
  1,500,000 
NR/NR
Beacon Lakes Community Development District Special Assessment, 6.9%, 5/1/35   
  1,538,385 
   
  500,000 
NR/Ba3
Capital Trust Agency Revenue, 7.75%, 1/1/41   
  555,380 
   
  1,000,000 
NR/NR
Florida Development Finance Corp., Educational Facilities Revenue, 6.0%, 9/15/40   
  1,055,770 
   
  2,000,000 
NR/NR
Florida Development Finance Corp., Educational Facilities Revenue, 7.625%, 6/15/41   
  2,309,780 
   
  1,000,000 
NR/NR
Florida Development Finance Corp., Educational Facilities Revenue, 7.75%, 6/15/42   
  1,127,020 
   
  1,000,000(b)
NR/WR
Hillsborough County Industrial Development Authority Revenue, 8.0%, 8/15/32   
  1,435,190 
   
  2,260,000 
NR/NR
Liberty County Subordinate Revenue, 8.25%, 7/1/28   
  2,290,691 
   
  2,500,000 
A-/A2
Miami-Dade County Florida Aviation Revenue, 5.5%, 10/1/41   
  2,850,075 
   
  1,000,000 
NR/NR
St. Johns County Industrial Development Authority Revenue, 5.25%, 1/1/26   
  949,150 
   
  2,000,000 
NR/NR
St. Johns County Industrial Development Authority Revenue, 5.375%, 1/1/40   
  1,776,940 
   
  5,000,000 
NR/Baa1
Tallahassee Health Facilities Revenue, 6.375%, 12/1/30   
  5,008,100 
         
$ 24,353,111 
       
Georgia - 2.7%
 
   
  4,240,000(c)
AA-/WR
Atlanta Georgia Water and Wastewater Revenue, RIB, 10.94%, 1/30/13 (144A) 
$ 4,761,520 
   
  500,000 
CCC+/NR
Clayton County Development Authority Revenue, 9.0%, 6/1/35   
  550,090 
   
  2,400,000 
NR/NR
Fulton County Residential Care Facilities Revenue, 5.0%, 7/1/27   
  2,365,176 
   
  1,100,000 
NR/NR
Fulton County Residential Care Facilities Revenue, 5.125%, 7/1/42   
  1,039,434 
         
$ 8,716,220 
       
Idaho - 1.5%
 
   
  5,000,000 
BBB+/Baa1
Power County Industrial Development Corp., 6.45%, 8/1/32   
$ 5,008,300 
           
       
Illinois - 14.1%
 
   
  1,000,000(a)
NR/NR
Illinois Finance Authority Revenue, 6.0%, 11/15/27   
$ 240,050 
   
  3,865,000 
BBB+/NR
Illinois Finance Authority Revenue, 6.0%, 8/15/38   
  4,374,484 
   
  2,000,000 
AA+/Aa2
Illinois Finance Authority Revenue, 6.0%, 8/15/39   
  2,351,780 
   
  4,000,000(a)
NR/NR
Illinois Finance Authority Revenue, 6.0%, 11/15/39   
  960,200 
   
  2,450,000 
NR/NR
Illinois Finance Authority Revenue, 6.375%, 5/15/17   
  2,452,548 

   
Principal
Amount
USD ($)
S&P/Moody's
Rating
 
Value
 
       
Illinois - (continued)
 
   
  2,500,000 
NR/Baa2
Illinois Finance Authority Revenue, 6.5%, 4/1/39   
  2,817,550 
   
  500,000 
NR/NR
Illinois Finance Authority Revenue, 7.0%, 5/15/18   
  502,585 
   
  1,700,000 
NR/NR
Illinois Finance Authority Revenue, 7.625%, 5/15/25   
  2,003,773 
   
  600,000 
NR/NR
Illinois Finance Authority Revenue, 7.75%, 5/15/30   
  702,558 
   
  2,000,000 
NR/NR
Illinois Finance Authority Revenue, 8.0%, 5/15/40   
  2,347,680 
   
  3,200,000 
NR/NR
Illinois Finance Authority Revenue, 8.0%, 5/15/46   
  3,756,288 
   
  4,000,000 
NR/NR
Illinois Finance Authority Revenue, 8.25%, 5/15/45   
  4,363,280 
   
  2,500,000 
NR/NR
Illinois Finance Authority Revenue, 8.25%, 2/15/46   
  2,710,950 
   
  16,880,000 
AAA/A3
Metropolitan Pier & Exposition Authority Dedicated State Tax Revenue, 0.0%, 6/15/22   
  15,527,237 
   
  1,515,000 
NR/NR
Southwestern Illinois Development Authority Revenue, 5.625%, 11/1/26   
  1,294,719 
         
$ 46,405,682 
       
Indiana - 1.1%
 
   
  3,570,000 
NR/NR
Vigo County Hospital Authority Revenue, 5.8%, 9/1/47 (144A) 
$ 3,680,813 
           
       
Louisiana - 2.1%
 
   
  1,500,000 
BBB-/Baa3
Louisiana Local Government Environmental Facilities & Community Development Authority Revenue, 6.75%, 11/1/32   
$ 1,685,925 
   
  5,000,000 
NR/Baa1
Louisiana Public Facilities Authority Revenue, 5.5%, 5/15/47   
  5,210,050 
         
$ 6,895,975 
       
Maine - 0.6%
 
   
  1,500,000 
NR/Baa3
Maine Health & Higher Educational Facilities Authority Revenue, 7.5%, 7/1/32   
$ 1,864,920 
           
       
Massachusetts - 6.4%
 
   
  7,100,000 
A/WR
Massachusetts Development Finance Agency Revenue, 5.75%, 1/1/42   
$ 9,266,707 
   
  2,250,000 
NR/NR
Massachusetts Development Finance Agency Revenue, 7.1%, 7/1/32   
  2,115,562 
   
  825,000 
AA/NR
Massachusetts Educational Financing Authority Revenue, 6.0%, 1/1/28   
  959,261 
   
  1,860,000 
AAA/Aaa
Massachusetts Health & Educational Facilities Authority Revenue, 5.5%, 7/1/32   
  2,668,970 
   
  1,000,000 
NR/Caa1
Massachusetts Health & Educational Facilities Authority Revenue, 6.0%, 10/1/23   
  1,000,960 
   
  4,500,000(a)
NR/NR
Massachusetts Health & Educational Facilities Authority Revenue, 6.5%, 1/15/38   
  22,590 
   
  5,000,000 
BB-/NR
Massachusetts Health & Educational Facilities Authority Revenue, 6.75%, 10/1/33   
  5,100,350 
         
$ 21,134,400 
       
Michigan - 3.2%
 
   
  935,000 
NR/NR
Doctor Charles Drew Academy Certificate of Participation, 5.7%, 11/1/36   
$ 680,456 
   
  1,500,000 
BB-/NR
John Tolfree Health System Corp. Revenue, 6.0%, 9/15/23   
  1,470,135 
   
  2,000,000 
BB+/NR
Kent Hospital Finance Authority Revenue, 6.25%, 7/1/40   
  2,088,460 
   
  5,830,000 
B-/NR
Michigan Tobacco Settlement Finance Authority, 6.0%, 6/1/48   
  4,770,980 

Principal
Amount
USD ($)
   
S&P/Moody's
Rating
     
Value
 
   
         
Michigan - (continued)
     
  1,410,000    
BBB/NR
 
Star International Academy Certificates of Participation, 6.125%, 3/1/37   
    1,424,128  
                $ 10,434,159  
           
Minnesota - 0.9%
       
  1,000,000    
NR/NR
 
Bloomington Port Authority, 9.0%, 12/1/35   
  $ 1,189,280  
  1,675,000    
BB-/NR
 
Duluth Economic Development Authority Health Care Facilities Revenue, 7.25%, 6/15/32   
    1,693,810  
                $ 2,883,090  
           
Montana - 0.1%
       
  1,600,000 (a)(e)  
NR/NR
 
Two Rivers Authority Revenue, 7.375%, 11/1/27   
  $ 237,696  
                     
           
Nevada - 0.0%
       
  2,000,000 (a)(e)  
NR/NR
 
Director of the State of Nevada Department of Business & Industry Revenue, 7.25%, 1/1/23   
  $ 20  
                     
           
New Jersey - 8.8%
       
  1,500,000    
NR/NR
 
New Jersey Economic Development Authority Revenue, 10.5%, 6/1/32 (144A) 
  $ 1,657,635  
  10,000,000       B/B3  
New Jersey Economic Development Authority Revenue, 6.25%, 9/15/29   
    10,039,900  
  6,150,000 (d)      B/B3  
New Jersey Economic Development Authority Revenue, 7.0%, 11/15/30   
    6,173,308  
  3,000,000       B-/B1  
Tobacco Settlement Financing Corp., 4.625%, 6/1/26   
    2,720,760  
  8,000,000 (b)  
AA+/Aaa
 
Tobacco Settlement Financing Corp., 6.75%, 6/1/39   
    8,435,360  
                  $ 29,026,963  
             
New Mexico - 1.2%
       
  1,500,000    
NR/NR
 
Otero County New Mexico Project Revenue, 6.0%, 4/1/23   
  $ 1,363,230  
  2,960,000    
NR/NR
 
Otero County New Mexico Project Revenue, 6.0%, 4/1/28   
    2,556,878  
                  $ 3,920,108  
             
New York - 8.6%
       
  2,000,000    
NR/NR
 
Chautauqua County Capital Resource Corp. Revenue, 8.0%, 11/15/30   
  $ 2,187,680  
  3,000,000    
NR/NR
 
Dutchess County Industrial Development Agency Revenue, 7.5%, 3/1/29   
    3,090,450  
  2,000,000    
BBB+/NR
 
Hempstead Local Development Corp. Revenue, 5.75%, 7/1/39   
    2,222,340  
  2,000,000    
BB/B2
 
New York City Industrial Development Agency Revenue, 5.25%, 12/1/32   
    1,955,860  
  2,000,000    
BB/B2
 
New York City Industrial Development Agency Revenue, 7.625%, 12/1/32   
    2,055,580  
  2,000,000    
NR/C
 
New York City Industrial Development Agency Revenue, 8.0%, 8/1/12   
    2,019,980  
  7,040,000 (d)  
AAA/WR
 
New York State Dormitory Authority Revenue, 13.219%, 5/29/14 (144A) 
    10,583,091  
  1,000,000    
NR/Ba1
 
New York State Dormitory Authority Revenue, 6.125%, 12/1/29   
    1,110,120  
  3,000,000    
NR/NR
 
Suffolk County Industrial Development Agency Revenue, 7.25%, 1/1/30   
    3,002,430  
                  $ 28,227,531  
             
North Carolina - 2.8%
       
  4,785,000    
NR/NR
 
Charlotte Special Facilities Revenue, 5.6%, 7/1/27   
  $ 4,356,073  
  4,795,000    
NR/NR
 
Charlotte Special Facilities Revenue, 7.75%, 2/1/28   
    4,802,576  
                  $ 9,158,649  
             
Oklahoma - 0.4%
       
  1,225,000 (a)  
NR/WR
 
Tulsa Airport Improvement Trust Revenue, 6.25%, 6/1/20   
  $ 1,249,500  
                       

   
Principal
Amount
USD ($)
S&P/Moody's
Rating
 
Value
 
       
Pennsylvania - 2.5%
 
   
  1,550,000 
NR/Baa2
Allegheny County Hospital Development Authority Revenue, 5.125%, 5/1/25   
$ 1,550,372 
   
  1,000,000 
CCC/NR
Columbia County Hospital Authority Health Care Revenue, 5.9%, 6/1/29   
  1,000,430 
   
  1,280,000(a)
NR/WR
Langhorne Manor Borough Higher Education Authority Revenue, 7.35%, 7/1/22   
  371,046 
   
  5,000,000 
B-/Caa2
Pennsylvania Economic Development Financing Authority Solid Waste Disposal Revenue, 6.0%, 6/1/31   
  4,830,100 
   
  500,000 
BBB+/NR
Pennsylvania Higher Educational Facilities Authority Revenue, 5.4%, 7/15/36   
  516,795 
         
$ 8,268,743 
       
Rhode Island - 2.1%
 
   
  6,000,000(e)
NR/NR
Central Falls Detention Facility Corp. Revenue, 7.25%, 7/15/35   
$ 5,162,280 
   
  1,500,000 
NR/NR
Rhode Island Health & Educational Building Corp Revenue, 8.375%, 1/1/46   
  1,757,520 
         
$ 6,919,800 
       
South Carolina - 1.2%
 
 
  3,850,000(b)
BBB+/Baa1
South Carolina Jobs Economic Development Authority Revenue, 6.375%, 8/1/34   
$ 4,085,389 
           
       
Tennessee - 1.5%
 
   
  4,600,000 
BBB+/NR
Sullivan County Health, Educational & Housing Facilities Board Revenue, 5.25%, 9/1/36   
$ 4,800,376 
           
       
Texas - 15.3%
 
   
  1,345,000 
NR/Caa2
Bexar County Housing Finance Corp., 8.0%, 12/1/36   
$ 928,776 
   
  2,500,000 
BB+/Ba1
Central Texas Regional Mobility Authority Revenue, 6.75%, 1/1/41   
  2,862,100 
   
  4,000,000 
NR/NR
Decatur Hospital Authority Revenue, 7.0%, 9/1/25   
  4,288,760 
   
  725,078(a)(e)
NR/NR
Gulf Coast Industrial Development Authority, 7.0%, 12/1/36   
  6,896 
   
  3,750,000 
B-/B3
Houston Airport System Special Facilities Revenue, 5.7%, 7/15/29   
  3,714,525 
   
  5,340,000 
NR/NR
Lubbock Health Facilities Development Corp. Revenue, 6.625%, 7/1/36   
  5,578,538 
   
  10,000,000 
BBB+/A3
North Texas Tollway Authority Revenue, 5.75%, 1/1/33   
  11,054,400 
   
  2,810,000(d)
AAA/Aaa
Northside Independent School District G.O., 11.52%, 9/29/12 (144A) 
  3,395,660 
   
  1,500,000 
NR/NR
Red River Health Facilities Development Corp. Revenue, 8.0%, 11/15/41   
  1,705,335 
   
  7,040,000(d)
AA+/Aaa
State of Texas G.O., 12.464%, 4/1/13   
  9,210,995 
   
  2,000,000 
NR/NR
Tarrant County Cultural Education Facilities Finance Corp. Revenue, 8.0%, 11/15/34   
  2,256,580 
   
  1,000,000 
NR/NR
Tarrant County Cultural Education Facilities Finance Corp. Revenue, 8.125%, 11/15/39   
  1,112,620 
   
  1,500,000 
NR/NR
Tarrant County Cultural Education Facilities Finance Corp. Revenue, 8.25%, 11/15/44   
  1,675,125 
   
  2,500,000 
NR/NR
Travis County Health Facilities Development Corp. Revenue, 7.125%, 1/1/46   
  2,615,200 
         
$ 50,405,510 
       
Vermont - 0.5%
 
   
  1,500,000(b)
A-/Baa1
Vermont Educational & Health Buildings Financing Agency Revenue, 6.0%, 10/1/28   
$ 1,599,135 
           

   
Principal
Amount
USD ($)
S&P/Moody's
Rating
 
Value
 
       
Virginia - 0.3%
 
   
  1,000,000 
BBB/Ba1
Peninsula Ports Authority Revenue, 6.0%, 4/1/33   
$ 1,021,970 
           
       
Washington - 10.0%
 
   
  4,710,000 
A+/A2
Spokane Public Facilities District Hotel/Motel Tax & Sales Revenue, 5.75%, 12/1/27   
$ 4,978,140 
   
  14,315,000(f)
AA+/Aa1
State of Washington G.O., 0.0%, 6/1/22   
  11,259,034 
   
  7,025,000 
BBB/Baa1
Tobacco Settlement Authority Revenue, 6.625%, 6/1/32   
  7,292,723 
   
  3,795,000 
A/A2
Washington State Health Care Facilities Authority Revenue, 6.0%, 1/1/33   
  4,276,358 
   
  5,000,000 
NR/NR
Washington State Housing Finance Committee Nonprofit Revenue, 5.625%, 1/1/27   
  5,041,500 
         
$ 32,847,755 
       
West Virginia - 0.3%
 
   
  745,000 
NR/NR
West Virginia Hospital Finance Authority Hospital Revenue, 9.125%, 10/1/41   
$ 915,434 
           
       
Wisconsin - 1.8%
 
   
  2,320,000(g)
NR/NR
Aztalan Township, 0.0%,     
$ – 
   
  2,500,000 
NR/NR
Wisconsin Public Finance Authority  Revenue, 8.25%, 6/1/46   
  2,962,000 
   
  1,500,000 
NR/NR
Wisconsin Public Finance Authority Revenue, 8.375%, 6/1/20   
  1,518,000 
   
  1,500,000 
NR/NR
Wisconsin Public Finance Authority Revenue, 8.625%, 6/1/47   
  1,573,125 
         
$ 6,053,125 
       
TOTAL TAX EXEMPT OBLIGATIONS
 
       
(Cost $363,011,069)
$ 404,245,182 
           
       
MUNICIPAL COLLATERALIZED DEBT OBLIGATION -  1.9% of Net Assets
 
   
  10,000,000(d)(e)
NR/NR
Non-Profit Preferred Funding Trust I, 6.75%, 9/15/37 (144A) 
$ 6,329,000 
           
       
TOTAL MUNICIPAL COLLATERALIZED DEBT OBLIGATION
 
       
(Cost  $10,000,000)
$ 6,329,000 
           
       
TOTAL INVESTMENTS IN SECURITIES - 124.9%
 
       
(Cost - $373,011,069) (h)(i)
$ 410,574,182 
       
OTHER ASSETS AND LIABILITIES -5.8%
$ 19,114,004 
       
PREFERRED SHARES AT REDEMPTION VALUE,
INCLUDING DIVIDENDS PAYABLE - (30.7)%
$ (100,999,612)
       
NET ASSETS APPLICABLE TO
COMMON SHAREHOLDERS -100.0%
$ 328,688,574 
 
 
 
NR
 
Security not rated by S&P or Moody's.
RIB
 
Residual Interest Bonds.
GO
 
General Obligation.
WR
 
Rating Withdrawn.
(144A)
 
Security is exempt from registration under Rule 144A of the Securities Act of 1933.  Such securities may be resold normally to qualified institutional buyers in a transaction exempt from registration. At July 31, 2012, the value of these securities amounted to $43,522,278, or 13.2% of total net assets applicable to common shareowners.
 
 
 
(a)
Security is in default and is non income producing.
(b)
Prerefunded bonds have been collateralized by U.S. Treasury or U.S. Government Agency securities which are held in escrow to pay interest and principal on the tax exempt issue and to retire the bonds in full at the earliest refunding date.
(c)
Residual Interest Bonds. The interest rate is subject to change periodically and inversely based upon prevailing market rates. The interest rate shown is the rate July 31, 2012.
(d)
The interest rate is subject to change periodically. The interest is shown is the rate at July 31, 2012.
(e)
Indicates a security that has been deemed as illiquid.  The aggregate cost of illiquid securities is $20,086,629.  The aggregate fair value of $11,735,892 represents 3.6% of total net assets applicable to common shareholders.
(f)
Security issued with a zero coupon.  Income is recognized through accretion of discount.
(g)
Security is fair valued
 
 

(h)
The concentration of investments by type of obligation/ market sector is as follows  (unaudited):
 
 
   Insured
 
NATL-RE
5.0
%
 
FSA
3.6
 
 
NATL-RE FGIC
2.7
 
 
AMBAC GO OF INSTN
2.3
 
 
PSF-GTD
0.8
 
 
GO OF INSTN
0.7
 
 
   Revenue Bonds:
 
Health Revenue
17.3
 
 
Other Revenue
15.5
 
 
Facilities Revenue
13.9
 
 
Tobacco Revenue
13.6
 
 
Development Revenue
8.1
 
 
Education Revenue
6.1
 
 
Airport Revenue
5.9
 
 
Transportation Revenue
2.7
 
 
Pollution Control Revenue
1.8
 
 
Utilities Revenue*
0.0
 
   
100.0
%
 
*       Amount rounds to less than 01.1%
(i)
At July 31, 2012, the net unrealized gain on investments based on cost for federal tax purposes of $373,011,069 was as follows:
 
   
 
Aggregate gross unrealized gain for all investments in which there is an excess of value over tax cost
$ 53,079,947 
 
Aggregate gross unrealized loss for all investments in which there is an excess of tax cost over value
  (15,516,826)
   
 
Net unrealized gain
$ 37,563,121 
     
For financial reporting purposes net unrealized gain on investments was
$ 37,563,121 and cost of investments aggregated  $373,011,069.
 
 
   
 
 
Principal amounts are denominated in U.S. dollars unless otherwise noted.
 
 
 
 




Various inputs are used in determining the value of the Trust's investments. These inputs are summarized in the three broad levels below.
 
   
Level 1 - quoted prices in active markets for identical securities
 
Level 2 - other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds
 
credit risks, etc.)
 
Level 3 - significant unobservable inputs (including the Trust's own assumptions in determining fair value of investments)
 
   
Generally, equity securities are categorized as Level 1, fixed income securities and senior loans are categorized as Level 2, and securities valued using fair value methods (other than prices supplied by independent pricing services) as level 3.
 
   
                         
   
Level 1
   
Level 2
   
Level 3
   
Total
 
Investments in Securities - Assets
 
TAX EXEMPT OBLIGATIONS:
  $     $ 397,638,711     $     $ 404,245,182  
MUNICIPAL COLLATERALIZED DEBT OBLIGATION:
          6,329,000             6,329,000  
Total Investments in Securities - Assets
  $     $ 403,967,711     $     $ 410,574,182  
   
 
 
 
 


ITEM 2. CONTROLS AND PROCEDURES.

(a) Disclose the conclusions of the registrant's principal executive officer or
officers and principal financial officer or officers, or persons performing
similar functions, about the effectiveness of the registrant's disclosure
controls and procedures (as defined in Rule 30a-3(c) under the Act (17 CFR
270.30a-3(c))) as of a date within 90 days of the filing date of the report
that includes the disclosure required by this paragraph, based on their
evaluation of these controls and procedures required by Rule 30a-3(b)
under the Act (17 CFR270.30a-3(b))) and Rule 13a-15(b) or 15d-15(b)
under the Exchange Act (17 CFR240.13a-15(b) or 240.15d-15(b)).

The registrant's principal executive officer and principal financial officer
have concluded that the registrant's disclosure controls and procedures are
effective based on their evaluation of these controls and procedures as of
a date within 90 days of the filing date of this report.

(b) Disclose any change in the registrant's internal controls over financial
reporting (as defined in Rule 30a-3(d) under the Act (17 CFR270.30a-3(d))
that occurred during the registrant's last fiscal quarter that has materially
affected, or is reasonably likely to materially affect, the registrant's
internal control over financial reporting.

There were no significant changes in the registrant's internal control over
financial reporting that occurred during the second fiscal quarter of the
period covered by this report that have materially affected, or are
reasonably likely to materially affect, the registrant's internal control
over financial reporting.



ITEM 3. EXHIBITS.

(a) A separate certification for each principal executive officer and principal
financial officer of the registrant as required by Rule 30a-2 under the Act
(17 CFR 270.30a-2).

Filed herewith.



<PAGE>


                                   SIGNATURES

                          [See General Instruction F]


Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, the registrant has duly caused this report to be
signed on its behalf by the undersigned, thereunto duly authorized.


(Registrant) Pioneer Municipal High Income Trust

By (Signature and Title)* /s/ John F. Cogan, Jr.
John F. Cogan, Jr, President

Date September 28, 2012


Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, this report has been signed below by the
following persons on behalf of the registrant and in the capacities and on the
dates indicated.


By (Signature and Title)* /s/ John F. Cogan, Jr.
John F. Cogan, Jr., President

Date September 28, 2012



By (Signature and Title)* /s/ Mark Bradley
Mark Bradley, Treasurer

Date September 28, 2012

* Print the name and title of each signing officer under his or her signature.