OMB APPROVAL OMB Number: 3235-0578 Expires: February 28, 2006 Estimated average burden hours per response..... 20.0 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) Dorothy E. Bourassa, 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, 2004 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. ITEM 1. Schedule of Investments. Pioneer Municipal High Income Trust SCHEDULE OF INVESTMENTS 7/31/04 (unaudited) Principal S&P/Moody's Amount Ratings Value TAX EXEMPT OBLIGATIONS - 127.6% OF NET ASSETS Alabama - 3.6% $ 10,000,000AAA/Aaa Birmingham Alabama General Obligation, 5.0%, 12/1/32 $ 10,000,700 1,500,0BBB/NR Camden Alabama Industrial Development Board, 6.125%, 12/1/24 1,565,940 $ 11,566,640 Arizona - 6.0% 5,000,0B+/Ba3 Apache County Industrial Development Authority, 5.85%, 3/1/28 $ 4,862,700 5,000,0B+/Ba3 Apache County Industrial Development Authority, 5.875%, 3/1/33 4,835,250 3,000,0NR/NR Maricopa County Industrial Development Authority, 7.875%, 4/1/27 3,072,690 5,880,0AA/Aa2 Salt River Project Agriculture Improvement and Power District Electric System Revenue, 5.0%, 1/1/31 5,895,758 500,NR/Baa2 Yavapai County Industrial Development Authority, 6.0%, 8/1/33 504,495 $ 19,170,893 California - 10.9% 7,270,0BBB/A3 California State General Obligation, 5.25%, 2/1/28 $ 7,330,196 5,150,0BBB/Baa3 Golden State Tobacco Securitization Corp., 7.8%, 6/1/42 5,227,816 7,000,0BBB/Baa3 Golden State Tobacco Securitization Corp., 7.875%, 6/1/42 7,139,160 4,000,0AAA/Aaa Palm Desert Financing Authority Tax Allocation Revenue, 5.0%, 4/1/30 3,988,240 3,000,0AAA/Aaa San Diego Unified School District, 5.0%, 7/1/25 3,028,950 2,500,0AAA/Aaa University of California Revenue, 5.0%, 5/15/25 2,533,550 7,000,0B+/NR Valley Health System Hospital Revenue, 6.5%, 5/15/25 5,874,750 $ 35,122,662 Connecticut - 1.6% 2,205,0BB/Ba1 Connecticut State Health & Educational Facilities Authority Revenue, 5.375%,$ 1,838,264 4,400,0BB/Ba1 Connecticut State Health & Educational Facilities Authority Revenue, 5.5%, 7/1 3,391,388 $ 5,229,652 District of Columbia - 3.4% 5,000,0BBB/Baa3 District of Columbia Tobacco Settlement Financing Corp., 6.5%, 5/15/33 $ 4,334,200 7,325,0BBB/Baa3 District of Columbia Tobacco Settlement Financing Corp., 6.75%, 5/15/40 6,480,647 $ 10,814,847 Florida - 4.5% 2,000,0NR/NR Beacon Lakes Community Development, 6.9%, 5/1/35 $ 2,074,380 2,300,0CCC-/Caa3 Hillsborough County Aviation Authority Revenue, 6.8%, 1/1/24 1,115,638 1,650,0BBB-/Baa2 Polk County Industrial Development Revenue, 5.85%, 12/1/30 1,631,058 2,000,0NR/NR Seminole Tribe Convention-A, 8.95%, 10/1/33 2,309,480 1,900,0NR/NR Seminole Tribe Convention-A, 10.0%, 10/1/33 2,263,527 5,000,0NR/Baa2 Tallahassee Health Facilities Revenue, 6.375%, 12/1/30 5,020,100 $ 14,414,183 Idaho - 1.6% 5,000,0BB+/Ba3 Power County Industrial Development Corp., 6.45%, 8/1/32 $ 5,101,650 Illinois - 3.9% 1,000,0NR/NR Centerpoint Intermodal Center, 8.0%, 6/15/23 (144A) $ 971,310 2,790,0CCC-/Ca Chicago Illinois O'Hare International Airport, 6.45%, 5/1/18 1,129,950 1,500,0NR/NR Illinois Health Facilities Authority Revenue, 6.9%, 11/15/33 1,477,545 16,880,(aAAA/Aaa Metropolitan Pier & Exposition Authority Dedicated State Tax Revenue, 0.0%, 6/15/22 9,091,399 $ 12,670,204 Indiana - 1.1% 4,300,000 CCC/Caa3 Indiana State Development Finance Authority Revenue, 5.75%, 10/1/11 $ 3,585,254 Pioneer Municipal High Income Trust SCHEDULE OF INVESTMENTS 7/31/04 (unaudited) (continued) Principal S&P/Moody's Amount Ratings Value Kentucky - 2.2% $ 7,050,00CCC-/Caa2 Kenton County Airport Revenue, 7.5%, 2/1/12 $ 5,693,369 1,965,000 CCC-/Caa2 Kenton County Airport Revenue, 7.5%, 2/1/20 1,491,690 $ 7,185,059 Massachusetts - 8.4% 2,435,000 AAA/Aaa Massachusetts Health & Educational Facilities Authority Revenue, 5.0%, 7/15/$ 2,437,070 7,050,000 AAA/Aaa Massachusetts Health & Educational Facilities Authority Revenue, 5.125%, 7/15/ 7,074,534 1,000,000 AA/NR Massachusetts Health & Educational Facilities Authority Revenue, 5.25%, 10/15/ 1,008,570 2,640,000 BBB/Baa3 Massachusetts Health & Educational Facilities Authority Revenue, 5.75%, 7/1/28 2,566,397 3,500,000 BBB/Baa3 Massachusetts Health & Educational Facilities Authority Revenue, 6.25%, 7/1/22 3,615,640 5,000,000 BBB-/NR Massachusetts Health & Educational Facilities Authority Revenue, 6.75%, 10/1/3 5,105,500 75,000 BB/NR Massachusetts State Development Finance Agency, 5.25%, 10/1/18 64,464 5,055,000 AA-/Aa3 Massachusetts State Housing Finance Agency, 5.25%, 12/1/33 4,987,566 $ 26,859,741 Michigan - 4.3% 1,500,000 BBB-/NR John Tolfree Health System Corp., 6.0%, 9/15/23 $ 1,424,400 4,010,000 BBB-/Baa3 Michigan State Hospital Finance Authority Revenue, 6.0%, 2/1/24 3,841,740 2,000,000 NR/NR Michigan State Hospital Finance Authority Revenue, 6.4%, 1/1/15 1,944,300 7,690,000 NR/NR Wayne Charter County Special Airport Facilities Revenue, 6.75%, 12/1/15 6,552,572 $ 13,763,012 Minnesota - 3.9% 13,260,000 NR/NR Minneapolis/St. Paul Metropolitan Airports, 7.0%, 4/1/25 $ 11,035,502 1,500,000 BB/Ba2 St. Paul Housing & Redevelopment Authority, 6.625%, 11/1/17 1,514,520 $ 12,550,022 Mississippi - 0.9% 3,000,000 BBB-/Ba1 Mississippi Business Finance Corp. Pollution Control Revenue, 5.9%, 5/1/22 $ 3,024,210 Missouri - 1.5% 5,500,000 NR/Ba3 St. Louis Industrial Development Authority Revenue, 7.25%, 12/15/35 $ 4,825,975 Nevada - 1.4% 1,000,000 BBB-/Baa2 Clark County Industrial Development Revenue, 5.45%, 3/1/38 $ 1,041,680 1,850,000 B-/NR Clark County Industrial Development Revenue, 5.5%, 10/1/30 1,581,768 2,000,000 NR/NR Nevada State Department of Business & Industry, 7.25%, 1/1/23 1,970,900 $ 4,594,348 New Hampshire - 0.9% 3,000,000 AAA/Aaa Manchester School Facilities Revenue, 5.125%, 6/1/28 $ 3,050,550 New Jersey - 8.0% 2,000,000 B/Caa2 New Jersey Economic Development Authority Revenue, 6.25%, 9/15/19 $ 1,584,780 11,700,000 B/Caa2 New Jersey Economic Development Authority Revenue, 6.25%, 9/15/29 8,744,346 1,000,000 B/Caa2 New Jersey Economic Development Authority Revenue, 6.4%, 9/15/23 783,510 6,150,000 B/Caa2 New Jersey Economic Development Authority Revenue, 7.0%, 11/15/30 4,816,373 10,750,000 BBB/Baa3 Tobacco Settlement Financing Corp., 6.75%, 6/1/39 9,683,600 $ 25,612,609 New Mexico - 1.3% 3,700,000 NR/NR New Mexico Hospital Equipment Loan Council, 6.4%, 6/1/16 $ 4,042,953 New York - 5.8% 2,000,000 A/NR New York City Industrial Development Agency, 5.375%, 6/1/23 $ 1,998,660 5,625,000 CCC/Caa2 New York City Industrial Development Agency, 6.9%, 8/1/24 3,503,194 5,000,000 AAA/Aaa New York City Trust Cultural Resources Revenue, 5.125%, 7/1/31 5,059,800 2,000,000 NR/NR Suffolk County Industrial Development Agency, 7.25%, 1/1/30 1,872,700 6,000,000 AAA/Aaa Triborough Bridge & Tunnel Authority Revenue, 5.25%, 11/15/30 6,154,800 $ 18,589,154 North Carolina - 1.4% 2,000,000 AA+/Aa2 Charlotte North Carolina Certificates of Participation, 5.0%, 6/1/33 $ 1,981,760 4,600,000 NR/NR Charlotte North Carolina Special Facilities Revenue, 7.75%, 2/1/28 2,415,000 $ 4,396,760 Pioneer Municipal High Income Trust SCHEDULE OF INVESTMENTS 7/31/04 (unaudited) (continued) Principal S&P/Moody's Amount Ratings Value Oklahoma - 4.9% $ 3,000,00B-/B1 Oklahoma Development Finance Authority Revenue, 5.625%, 8/15/19 $ 3,029,940 8,000,000 B-/B1 Oklahoma Development Finance Authority Revenue, 5.625%, 8/15/29 8,079,840 4,100,000 B-/Caa2 Tulsa Municipal Airport Revenue, 5.65%, 12/1/35 3,730,877 1,225,000 B-/Caa2 Tulsa Municipal Airport Revenue, 6.25%, 6/1/20 916,729 $ 15,757,386 Oregon - 4.8% 1,000,000 NR/NR Klamath Falls Electric Revenue, 5.75%, 1/1/13 $ 1,001,960 7,000,000 NR/NR Klamath Falls Electric Revenue, 6.0%, 1/1/25 6,764,030 7,500,000 NR/NR Western Generation Agency Cogeneration Project Revenue, 7.125%, 1/1/21 7,583,400 $ 15,349,390 Pennsylvania - 10.9% 1,550,000 NR/Baa1 Allegheny County Hospital Development Authority Revenue, 5.125%, 5/1/25 $ 1,326,180 12,300,000 B/B2 Allegheny County Hospital Development Authority Revenue, 9.25%, 11/15/30 13,782,150 2,500,000 BBB-/Baa2 Beaver County Industrial Development Authority, 7.625%, 5/1/25 2,642,900 1,000,000 BB-/NR Columbia County Hospital Authority Health Care Revenue, 5.9%, 6/1/29 786,270 5,000,000 BBB/Baa3 Delaware County Industrial Development Authority Revenue, 6.1%, 7/1/13 5,260,600 1,280,000 NR/B2 Langhorne Manor Borough Higher Education & Health Authority Revenue, 7.35%, 7/ 1,235,520 2,500,000 BBB+/NR Pennsylvania Higher Educational Facilities Authority Revenue, 5.4%, 7/15/36 2,459,550 2,230,000 AAA/Aaa Pennsylvania State Turnpike Commission, 5.0%, 7/15/10 2,435,517 5,000,000 BBB-/Baa2 Philadelphia Hospitals & Higher Education Facilities Authority Revenue, 6.5%, 5,000,300 $ 34,928,987 South Carolina - 8.7% 4,250,000 BBB/Baa2 Georgetown County Environmental Improvement Revenue, 5.95%, 3/15/14 $ 4,623,958 15,000,000 AA-/A1 Greenville County School District, 5.5%, 12/1/28 15,285,450 1,900,000 BBB/Baa2 South Carolina Jobs Economic Development Authority Revenue, 6.25%, 8/1/31 1,955,290 5,850,000 BBB/Baa2 South Carolina Jobs Economic Development Authority Revenue, 6.375%, 8/1/34 6,069,609 $ 27,934,307 Tennessee - 5.2% 7,000,000 BBB+/Baa2 Johnson City Health & Educational Facilities Board Hospital Revenue, 7.5%, 7$ 8,084,230 4,480,000 NR/Baa2 Knox County Health Educational & Housing Facilities Board Hospital Revenue, 6. 4,231,046 4,055,000 BBB/Baa2 Memphis-Shelby County Airport Authority Special Facilities Revenue, 5.05%, 9/1 4,236,218 $ 16,551,494 Texas - 7.7% 6,500,000 CCC/Caa2 Alliance Airport Authority Special Facilities Revenue, 7.0%, 12/1/11 $ 5,379,140 7,500,000 CCC/Caa2 Alliance Airport Authority Special Facilities Revenue, 7.5%, 12/1/29 5,137,275 1,345,000 NR/Baa3 Bexar County Housing Finance Corp., 8.0%, 12/1/36 1,395,747 5,500,000 CCC-/Caa2 Dallas-Fort Worth International Airport Revenue, 7.125%, 11/1/26 2,307,470 2,800,000 CCC-/Caa2 Dallas-Fort Worth International Airport Revenue, 7.6%, 11/1/11 1,378,496 750,000 CCC-/Caa2 Dallas-Fort Worth International Airport Revenue, 7.625%, 11/1/21 328,133 1,000,000 BB/NR Georgetown Health Facilities Development Corp., 6.25%, 8/15/29 939,250 3,750,000 B-/Caa2 Houston Airport System Special Facilities Revenue, 5.7%, 7/15/29 2,490,113 5,000,000 BBB/NR Lufkin Health Facilities Development Corp. 5.7%, 2/15/28 4,704,150 500,000 BBB/Baa2 Sabine River Authority Pollution Control Revenue, 6.15%, 8/1/22 518,515 $ 24,578,289 Vermont - 0.5% 1,500,000 A-/A3 Vermont Educational & Health Buildings Financing Agency Revenue, 6.0%, 10/1/$ 1,629,360 Virginia - 1.4% 1,000,000 BBB/Baa3 Peninsula Ports Authority, 6.0%, 4/1/33 $ 1,026,080 4,000,000 BB/NR Pocahontas Parkway Association of Virginia Toll Road Revenue, 5.5%, 8/15/28 3,355,320 $ 4,381,400 Washington - 5.3% 4,710,000 AAA/Aaa Spokane Public Facilities District Hotel/Motel Tax & Sales, 5.75%, 12/1/27 $ 5,112,564 7,025,000 BBB/Baa3 Tobacco Settlement Authority Washington, 6.625%, 6/1/32 6,199,211 14,315,000 AAA/Aaa Washington State General Obligation, 0.0%, 6/1/22 5,621,357 $ 16,933,132 Pioneer Municipal High Income Trust SCHEDULE OF INVESTMENTS 7/31/04 (unaudited) (continued) Principal S&P/Moody's Amount Ratings Value Wyoming - 1.6% $ 5,000,00BB+/Ba3 Sweetwater County Solid Waste Disposal Revenue, 6.9%, 9/1/24 $ 5,081,750 TOTAL TAX-EXEMPT OBLIGATIONS (Cost $405,609,905) $ 409,295,873 Shares TAX-EXEMPT MONEY MARKET MUTUAL FUND - 1.1% OF NET ASSETS 3,452,361 BlackRock Provident Institutional Municipal Fund $ 3,452,361 TOTAL TAX-EXEMPT MONEY MARKET MUTUAL FUND (Cost $3,452,361) $ 3,452,361 TOTAL INVESTMENTS IN SECURITIES - 128.7% (Cost $409,062,266) (b) (c) (d) $ 412,748,234 Other Assets in Excess of Liabilities - 2.8% $ 9,023,328 Preferred Shares at Redemption Value - (31.5)% $ -101,000,000 NET ASSETS APPLICABLE TO COMMON SHAREOWNERS - 100.0% $ 320,771,562 NR: Security not rated by S&P or Moody's. (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, 2004 the value of these securities amounted to $971,310 or 0.3% of net assets applicable to common shareholders. (a) Indicates a security that has a zero coupon that remains in effect until a predetermined date at which time the stated coupon rate becomes effective until final maturity. (b) The concentration of investments by type of obligation/market sector is as follows: Insured 16.1% General Obligation 1.8 Revenue Bonds: Health Revenue 25.0 Airport Revenue 18.1 Tobacco Revenue 9.5 Education Revenue 7.0 Pollution Control Revenue 6.9 Power Revenue 5.4 Development Revenue 3.3 Other 1.9 Facilities Revenue 1.6 Housing Revenue 1.6 Transportation Revenue 1.5 Utilities Revenue 0.3 100.0% (c) At July 31, 2004, the net unrealized gain on investments based on cost for federal income tax purposes of $408,488,776 was as follows: Aggregate gross unrealized gain for all investments in which there is an excess of value over tax cost $ $ 17,052,661 Aggregate gross unrealized loss for all investments in which there is an excess of tax cost over value -12,793,202 Net unrealized gain $ $ 4,259,459 For financial reporting purposses net unrealized gain on investments was $3,685,968 and cost of investments aggregated $409,062,266 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 certifying officers have determined that the registrant's disclosure controls and procedures are effective based on an evaluation of these controls and procedures as of a date within 90 days prior to 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 controls over financial reporting that occurred during the registrant's last fiscal quarter that have materially affected, or is 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. 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, 2004 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, 2004 By (Signature and Title)* /s/ Vincent Nave Vincent Nave, Treasurer Date September 28, 2004 * Print the name and title of each signing officer under his or her signature.