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

                                   FORM N-CSR

                   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:  May 1, 2012 through October 31, 2012


Form N-CSR is to be used by management investment companies to file reports with
the Commission not later than 10 days after the transmission to stockholders of
any report that is required to be transmitted to stockholders under Rule 30e-1
under the Investment Company Act of 1940 (17 CFR 270.30e-1).  The Commission may
use the information provided on Form N-CSR in its regulatory, disclosure review,
inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-CSR,
and the Commission will make this information public. A registrant is not
required to respond to the collection of information contained in Form N-CSR
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. REPORTS TO SHAREOWNERS.


                       Pioneer Municipal High
                       Income Trust

--------------------------------------------------------------------------------
                       Semiannual Report | October 31, 2012
--------------------------------------------------------------------------------

                       Ticker Symbol:   MHI

                       [LOGO] PIONEER
                              Investments(R)
<PAGE>

                      visit us: us.pioneerinvestments.com
<PAGE>

Table of Contents

Letter to Shareowners                                                          2

Portfolio Management Discussion                                                4

Portfolio Summary                                                             10

Prices and Distributions                                                      11

Performance Update                                                            12

Schedule of Investments                                                       13

Financial Statements                                                          24

Financial Highlights                                                          27

Notes to Financial Statements                                                 29

Trustees, Officers and Service Providers                                      37

            Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 1
<PAGE>

President's Letter

Dear Shareowner,

The U.S. stock market rallied sharply through the third quarter of 2012 amid a
sluggish, but nonetheless growing, U.S. economy. We have been cautiously
optimistic about the U.S. from the start of the year, and the economic data
continue to be encouraging. The housing and auto sectors are benefitting from
record-low interest rates. The climate for consumer and business credit has
improved, and inflation appears to be subdued. While corporate profits slowed in
the third quarter, many U.S. companies continue to have strong balance sheets
and to pay attractive dividends* compared to fixed-income securities.

All of these factors contributed to gains for investors who owned riskier
assets, including equities and higher-yielding corporate bonds. Year to date
through the end of the third quarter, the Standard & Poor's 500 Index returned
16.35%. In fixed income, the Bank of America Merrill Lynch High Yield Master II
Index was up by 12.02% during the same period, while the Barclays Capital
Aggregate Bond Index gained 3.99%. Treasury bonds, by contrast, generated a
comparatively sluggish return of 1.70%, as measured by the Barclays Capital
Intermediate Treasuries Index.

Despite this generally positive picture during the first three quarters of 2012,
investors face powerful macroeconomic challenges in the months ahead. These
include the threat of a so-called "fiscal cliff" in the U.S. budget process
after the November elections, the European sovereign-debt crisis, and slowing
growth in both Europe and China. Investors can continue to count on market
volatility tied to these factors, although we remain optimistic that the
underlying economic trends are moving in the right direction.

At Pioneer, we have long advocated the benefits of staying diversified and
investing for the long term. And while diversification alone does not assure a
profit or protect against loss in a declining market, we believe in actively
seeking out opportunities in undervalued securities and sectors around the
globe. Our advice, as always, is to work closely with a trusted financial
advisor to discuss your goals and work together to develop an investment
strategy that meets your individual needs. There is no single best strategy that
works for every investor.

*   Dividends are not guaranteed.

2 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

Pioneer's investment professionals focus on finding good opportunities in both
equity and bond markets using the same disciplined investment approach we have
used since 1928. Our strategy is to identify undervalued individual securities
with the greatest potential for success, carefully weighing risk against reward.
Our teams of investment professionals continually monitor and analyze the
relative valuations of different sectors and securities globally to help build
portfolios that we believe can help you achieve your investment goals.

We invite you to learn more about Pioneer and our time-tested approach to
investing by consulting with your financial advisor or visiting us online at
us.pioneerinvestments.com. We greatly appreciate your trust in us, and we thank
you for investing with Pioneer.

Sincerely,

/s/ Daniel K. Kingsbury

Daniel K. Kingsbury
President and CEO
Pioneer Investment Management USA, Inc.

Any information in this shareowner report regarding market or economic trends or
the factors influencing the Trust's historical or future performance are
statements of opinion as of the date of this report. These statements should not
be relied upon for any other purposes. Past performance is no guarantee of
future results, and there is no guarantee that market forecasts discussed will
be realized.

            Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 3
<PAGE>

Portfolio Management Discussion | 10/31/12

Strong investor demand and limited supply helped produce solid returns from
municipal bond investments during the six months ended October 31, 2012. In the
following interview, David Eurkus discusses the factors that influenced the
performance of Pioneer Municipal High Income Trust during the six-month period.
Mr. Eurkus, senior vice president and portfolio manager at Pioneer, is
responsible for the daily management of the Trust.

Q   How did Pioneer Municipal High Income Trust perform during the six months
    ended October 31, 2012?

A   Pioneer Municipal High Income Trust produced a total return of 8.33% at net
    asset value, and 7.53% at market price during the six months ended October
    31, 2012. During the same period, the Trust's benchmarks, the Barclays
    Capital High Yield Municipal Bond Index and the Barclays Capital Municipal
    Bond Index, returned 7.45% and 3.34%, respectively. The Barclays Capital
    High Yield Municipal Bond Index is designed to track the performance of
    lower-rated municipal bonds. The Barclays Capital Municipal Bond Index is
    designed to track the performance of investment-grade municipal bonds.
    During the same six months ended October 31, 2012, the average return (at
    market price) of the 12 closed end funds in Lipper's High Yield Municipal
    Debt Closed End Funds category (which may or may not be leveraged) was
    8.75%.

    Unlike the Trust, the two Barclays Capital municipal indices do not use
    leverage. While the use of leverage can increase investment opportunity, it
    also can increase investment risk.

    The shares of the Trust were selling at a 9.0% premium to net asset value at
    the end of the period.

    On October 31, 2012, the standardized 30-day SEC yield on the Trust's shares
    was 2.83%.

Q   How would you describe the investment environment for municipal bonds during
    the six months ended October 31, 2012?

A   The municipal market enjoyed healthy inflows of new money during the six
    months ended October 31, 2012, from both traditional investors seeking tax
    advantages and institutional investors who were attracted by the competitive
    yields available from municipal securities compared with taxable
    investments. During the period, both investment-grade and higher-yielding,
    below-investment-grade municipal securities produced more

4 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

    income than comparable-quality and similar-maturity taxable securities, on
    an after-tax basis. As demand increased during the six-month period, the
    supply of municipal securities remained limited. As a consequence, municipal
    bond prices rose and interest rates declined, delivering total returns in
    the asset class that often were superior to those available in the taxable
    market. In addition to offering attractive relative values, municipal
    revenue bonds continued to be perceived as a relatively safe place for
    investors' money.

Q   What investment strategies did you pursue during the six months ended
    October 31, 2012, and how did the strategies affect the Trust's performance?

A   In a favorable market for municipal bonds, the Trust outperformed its two
    benchmarks, aided by quality security selection in both investment-grade and
    high-yield municipals, and the Trust's longer-duration positioning as
    compared with the two Barclays Capital municipal indices' weighted average
    duration. The longer-duration positioning helped the Trust to capture price
    gains as interest rates declined during the period.

    We kept the Trust fully invested during the six-month period and maintained
    a duration positioning that was longer than that of the benchmarks. In
    addition, the Trust's portfolio of investments included many established
    positions with adequate call protection that had much higher yields than
    those currently available. Call protection limits the issuers' ability to
    pre-pay their debt in order to refinance into lower-yielding substitutes.

    During the period, we maintained the Trust's traditional emphasis on project
    revenue bonds, which are secured by dedicated revenue streams from specific
    projects, such as hospitals or airport facilities. We focus the Trust's
    investments on these securities because of the reliability of their funding
    sources as compared with general obligation bonds, which do not require
    dedicated revenue streams and can be more affected by credit rating
    downgrades or the general fiscal problems of a municipality or agency.

    At the end of the period on October 31, 2012, health care revenue bonds
    represented the largest allocation in the Trust's total investment
    portfolio, at 17.1% of invested assets, followed by insurance revenue bonds,
    which accounted for 14.9% of the Trust's total investment portfolio. Other
    project revenue allocations in the Trust's portfolio included those in
    education, housing, transportation and pollution control facilities.

    As of October 31, 2012, 44.8% of the Trust's total investment portfolio was
    invested in securities with investment-grade credit ratings, while 55.2% of
    the Trust's total investment portfolio was held in high-yield securities.

            Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 5
<PAGE>

Q   What types of investments had a material effect on the Trust's performance
    during the six months ended October 31, 2012?

A   The Trust's performance during the period benefited from strong results
    generated by both the investment-grade and high-yield allocations in the
    portfolio, across a range of areas, including the hospital/health care
    sector and the transportation and industrial development groups. We believe
    the Trust's performance during the period provides evidence of the value of
    our disciplined investment process, which relies on basic, fundamental
    research and the analysis of individual securities as well as the
    reliability of the securities' funding sources.

    Among individual Trust holdings during the period, standout performers
    included a British Airways transportation revenue bond issued in New York
    and an industrial development authority security issued by the Pennsylvania
    Economic Development Authority (backed by a U.S. Gypsum project). In the
    hospital/health care sector, the Trust saw positive results from several
    Massachusetts Health and Education Authority bonds. The Trust owned a
    security backed by the Mohegan Sun Casino in Connecticut, which also fared
    well during the period, as did holdings of several state revenue bonds
    backed by proceeds from tobacco liability settlements.

    Among the Trust's investments that detracted from results during the period
    were bonds backed by revenues of two continuing care retirement communities,
    one in Nassau County, New York, and one issued by the Illinois state
    financing authority.

Q   How did the level of leverage employed by the Trust change over the six
    months ended Sept. 30, 2012?

A   At the end of the six-month period ended October 31, 2012, 23.3% of the
    Trust's total managed assets were financed by leverage, compared with 24.1%
    of the Trust's total managed assets financed by leverage at the start of the
    period on May 1, 2012. The decrease was due to changes in the values of
    securities in which the Trust invested.

Q   What is your investment outlook?

A   We continue to see what we believe to be good values and attractive
    opportunities in the municipal market, both in high-yield and investment-
    grade securities. We believe we will see in the future the continued need
    for financing of essential projects, and that need should provide quality
    investment opportunities for those who focus on fundamental research of the
    strengths and financial reliability of each proposed project. We think
    credit research will remain essential for investment success.

6 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

    The municipal markets as well as the capital markets in general do face a
    number of issues that can affect values, including the continuing political
    debate in the U.S. over the country's national debt, levels of taxation, and
    discretionary spending policies.

    We plan to stay focused on intensive, independent research when selecting
    securities for the Trust's portfolio, looking at the different sectors
    involved in public finance and examining which areas we believe are most
    likely to have secure revenues, and which services are considered to be most
    essential. We are watching carefully for new areas of investment
    opportunity, which may include financing for charter schools, seaport
    facility expansions, toll road construction and maintenance, and energy
    production. In the current environment, we also will be paying close
    attention to which type of projects may be affected by any change in federal
    tax or spending policies.

Please refer to the Schedule of Investments on pages 13-23 for a full listing of
Trust securities.

            Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 7
<PAGE>

Investments in high-yield or lower-rated securities are subject to greater-than-
average risk.

The Trust may invest in securities of issuers that are in default or that are in
bankruptcy.

A portion of income may be subject to state, federal, and/or alternative minimum
tax. Capital gains, if any, are subject to a capital gains tax.

When interest rates rise, the prices of debt securities held by the Trust will
generally fall. Conversely, when interest rates fall the prices of debt
securities held by the Trust generally will rise.

By concentrating in municipal securities, the Trust is more susceptible to
adverse economic, political or regulatory developments than is a portfolio that
invests more broadly.

Investments in the Trust are subject to possible loss due to the financial
failure of the issuers of the underlying securities and the issuers' inability
to meet their debt obligations.

The Trust may invest up to 20% of its total assets in illiquid securities.
Illiquid securities may be difficult to dispose of at a fair price at the times
when the Trust believes it is desirable to do so, and their market price is
generally more volatile than that of more liquid securities. Illiquid securities
are also more difficult to value and investment of the Trust's assets in
illiquid securities may restrict the Trust's ability to take advantage of market
opportunities.

The Trust uses leverage through the issuance of preferred shares. Leverage
creates significant risks, including the risk that the Trust's incremental
income or capital appreciation will not be sufficient to cover the cost of
leverage, which may adversely affect the return for the holders of common
shares. Since February of 2008, regularly scheduled auctions for the Trust's
preferred shares have failed and preferred shareowners have not been able to
sell their shares at auction. The Board of Trustees of the Trust has considered,
and continues to consider, this issue.

The Trust is required to maintain certain regulatory and rating agency asset
coverage requirements in connection with its outstanding preferred shares. In
order to maintain required asset coverage levels, the Trust may be required to
alter the composition of its investment portfolio or take other actions, such as
redeeming preferred shares with the proceeds from portfolio transactions, at
what might be inopportune times in the market. Such actions could reduce the net
earnings or returns to holders of the Trust's common shares over time.

Risks of investing in the Trust are discussed in greater detail in the Trust's
original offering prospectus and in shareowner reports issued from time to time.

These risks may increase share price volatility.

Past performance is no guarantee of future results, and there is no guarantee
that market forecasts discussed will be realized.

8 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

Any information in this shareowner report regarding market or economic trends or
the factors influencing the Trust's historical or future performance are
statements of opinion as of the date of this report. These statements should not
be relied upon for any other purposes.

            Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 9
<PAGE>

Portfolio Summary | 10/31/12

Portfolio Diversification
--------------------------------------------------------------------------------
(As a percentage of total investment portfolio)

[THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL]

<TABLE>
<CAPTION>
<S>                                                                       <C>
Health Care Revenue Bonds                                                 17.0%
Other Revenue Bonds                                                       16.2%
Insured                                                                   14.9%
Facilities Revenue Bonds                                                  13.9%
Tobacco Revenue Bonds                                                     13.7%
Development Revenue Bonds                                                  8.0%
Education Revenue Bonds                                                    6.2%
Airport Revenue Bonds                                                      5.6%
Transportation Revenue Bonds                                               2.7%
Pollution Control Revenue Bonds                                            1.8%
Utilities Revenue Bonds                                                    0.0%*
</TABLE>

*   Amount is less than 0.1%

Portfolio Quality
--------------------------------------------------------------------------------
(As a percentage of total investment portfolio; based on Standard & Poor's
ratings)

[THE FOLLOWING DATA WAS REPRESENTED AS A PIE CHART IN THE PRINTED MATERIAL]

<TABLE>
<CAPTION>
<S>                                                                        <C>
NR                                                                         38.7%
AA                                                                         14.3%
BBB                                                                        13.9%
AAA                                                                        11.1%
B                                                                          10.7%
BB                                                                          5.8%
A                                                                           5.5%
</TABLE>

Bond ratings are ordered highest to lowest in portfolio. Based on Standard &
Poor's measures, AAA (highest possible rating) through BBB are considered
investment grade; BB or lower ratings are considered non-investment grade. Cash
equivalents and some bonds may not be rated.

The portfolio is actively managed and current holdings may be different.

10 Largest Holdings
--------------------------------------------------------------------------------
(As a percentage of long-term holdings)*

<TABLE>
<CAPTION>
<S>    <C>                                                                                   <C>
  1.   Metropolitan Pier & Exposition Authority Dedicated State Tax Revenue, 0.0%, 6/15/22   3.77%
--------------------------------------------------------------------------------------------------
  2.   Lehman Municipal Trust Receipts Revenue, 11.545%, 8/21/35                             3.34
--------------------------------------------------------------------------------------------------
  3.   State of Washington, GO, 0.0%, 6/1/22                                                 2.71
--------------------------------------------------------------------------------------------------
  4.   North Texas Tollway Authority Transportation Revenue, 5.75%, 1/1/33                   2.66
--------------------------------------------------------------------------------------------------
  5.   New York State Dormitory Authority Revenue, 13.073%, 5/29/14 (144A)                   2.53
--------------------------------------------------------------------------------------------------
  6.   Lehman Municipal Trust Receipts Revenue, RIB, 10.829%, 9/20/28 (144A)                 2.40
--------------------------------------------------------------------------------------------------
  7.   Massachusetts Development Finance Agency Revenue, 5.75%, 1/1/42                       2.26
--------------------------------------------------------------------------------------------------
  8.   State of Texas, GO, 12.332%, 4/1/13                                                   2.17
--------------------------------------------------------------------------------------------------
  9.   Tobacco Settlement Financing Corp., Revenue, 6.75%, 6/1/39                            1.99
--------------------------------------------------------------------------------------------------
 10.   Tobacco Settlement Authority Revenue, 6.625%, 6/1/32                                  1.76
--------------------------------------------------------------------------------------------------
</TABLE>

*   This list excludes temporary cash investments. The portfolio is actively
    managed, and current holdings may be different. The holdings listed should
    not be considered recommendations to buy or sell any security listed.

10 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

Prices and Distributions | 10/31/12

Market Value per Common Share
--------------------------------------------------------------------------------

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
                                        10/31/12                    4/30/12
--------------------------------------------------------------------------------
<S>                                      <C>                    <C>
                                         $16.04                      $15.49
--------------------------------------------------------------------------------
       Premium                            9.0%                         9.7%
--------------------------------------------------------------------------------
</TABLE>

Net Asset Value per Common Share
--------------------------------------------------------------------------------

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
                                        10/31/12                    4/30/12
--------------------------------------------------------------------------------
<S>                                      <C>                         <C>
                                         $14.72                      $14.12
--------------------------------------------------------------------------------
</TABLE>

Distributions per Common Share
--------------------------------------------------------------------------------

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
                       Net Investment          Short-Term       Long-Term
                           Income             Capital Gains    Capital Gains
--------------------------------------------------------------------------------
<S>                       <C>                     <C>             <C>
   5/1/12 - 10/31/12      $0.570                  $  --           $  --
--------------------------------------------------------------------------------
</TABLE>

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 11
<PAGE>

Performance Update | 10/31/12

Investment Returns
--------------------------------------------------------------------------------

The mountain chart on the right shows the change in market value, including
reinvestment of dividends and distributions, of a $10,000 investment made in
common shares of Pioneer Municipal High Income Trust, compared to that of the
Barclays Capital Municipal Bond Index and Barclays Capital High Yield Municipal
Bond Index.

<TABLE>
<CAPTION>
Average Annual Total Returns
(As of October 31, 2012)
--------------------------------------------------------------------------------
                                          Net Asset        Market
Period                                    Value (NAV)      Price
--------------------------------------------------------------------------------
<S>                                       <C>              <C>
Life-of-Trust
(7/17/2003)                                7.66%            8.13%
5 Years                                    7.15            10.06
1 Year                                    16.52            21.22
--------------------------------------------------------------------------------
</TABLE>

[THE FOLLOWING DATA WAS REPRESENTED AS A MOUNTAIN CHART IN THE PRINTED MATERIAL]

Market Value of $10,000 Investment

<TABLE>
<CAPTION>
              Pioneer Municipal   Barclays Capital High Yield   Barclays Capital
              High Income Trust   Municipal Bond Index          Municipal Bond Index
<S>           <C>                 <C>                           <C>
7/31/2003     $     10,000        $     10,000                  $      10,000
10/31/2003    $     10,097        $     10,419                  $      10,319
10/31/2004    $     10,504        $     11,446                  $      10,941
10/31/2005    $     11,261        $     12,522                  $      11,219
10/31/2006    $     11,991        $     14,009                  $      11,863
10/31/2007    $     12,789        $     14,326                  $      12,209
10/31/2008    $      8,865        $     11,614                  $      11,805
10/31/2009    $     13,395        $     13,303                  $      13,411
10/31/2010    $     16,540        $     15,147                  $      14,454
10/31/2011    $     17,043        $     15,656                  $      15,001
10/31/2012    $     20,660        $     18,307                  $      16,355
</TABLE>

Call 1-800-225-6292 or visit us.pioneerinvestments.com for the most recent
month-end performance results. Current performance may be lower or higher than
the performance data quoted.

Performance data shown represents past performance. Past performance is no
guarantee of future results. Investment return and market price will fluctuate,
and your shares may trade below NAV due to such factors as interest rate changes
and the perceived credit quality of borrowers.

Total investment return does not reflect broker sales charges or commissions.
All performance is for common shares of the Trust.

Closed-end funds, unlike open-end funds, are not continuously offered. There is
a one-time public offering and once issued, shares of closed-end funds are sold
in the open market through a stock exchange and frequently trade at prices lower
than their NAV. NAV is total assets less total liabilities which includes
preferred shares, divided by the number of common shares outstanding.

When NAV is lower than market price, dividends are assumed to be reinvested at
the greater of NAV or 95% of the market price. When NAV is higher, dividends are
assumed to be reinvested at prices obtained under the Trust's dividend
reinvestment plan.

The performance table and graph do not reflect the deduction of fees and taxes
that a shareowner would pay on Trust distributions or the sale of Trust shares.

The Barclays Capital Municipal Bond Index is a broad measure of the municipal
bond market. The Barclays Capital High Yield Municipal Bond Index totals over
$26 billion in market value and maintains over 1300 securities. Municipal bonds
in this index have the following requirements: maturities of one year or
greater, sub investment grade (below Baa or non-rated), fixed coupon rate,
issued after 12/31/90, deal size over $20 million, and maturity size of at least
$3 million. Index returns are calculated monthly, assume reinvestment of
dividends and, unlike Trust returns, do not reflect any fees, expenses or sales
charges.

The indices do not employ leverage. It is not possible to invest directly in the
indices.

12 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

Schedule of Investments | 10/31/12 (unaudited)

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------
 Principal
 Amount            S&P/Moody's
 USD ($)           Ratings                                                         Value
-----------------------------------------------------------------------------------------------
<S>                     <C>       <C>                                              <C>
                                  TAX EXEMPT OBLIGATIONS --
                                  123.8% of Net Assets
                                  Alabama -- 2.4%
    2,500,000             B-/B2   Alabama Industrial Development Authority
                                  Solid Waste Disposal Revenue, 6.45%,
                                  12/1/23                                          $  2,499,650
    1,000,000             NR/NR   Huntsville-Redstone Village Special Care
                                  Facilities Financing Authority Nursing Home
                                  Revenue, 5.5%, 1/1/28                               1,013,270
    4,500,000             NR/NR   Huntsville-Redstone Village Special Care
                                  Facilities Financing Authority Nursing Home
                                  Revenue, 5.5%, 1/1/43                               4,507,920
                                                                                   ------------
                                                                                   $  8,020,840
-----------------------------------------------------------------------------------------------
                                  Arizona -- 0.7%
      984,000           NR/Baa3   Pima County Industrial Development Authority
                                  Education Revenue, 6.75%, 7/1/31                 $    985,191
      950,000           NR/Baa3   Pima County Industrial Development Authority
                                  Education Revenue, 7.25%, 7/1/31                      951,871
      500,000           NR/Baa2   Yavapai County Industrial Development Authority
                                  Medical Revenue, 6.0%, 8/1/33                         517,465
                                                                                   ------------
                                                                                   $  2,454,527
-----------------------------------------------------------------------------------------------
                                  California -- 12.3%
    3,000,000(a)          NR/A1   Abag Finance Authority for Nonprofit Corp.
                                  Revenue, 5.75%, 7/1/37                           $  3,480,270
    5,100,000             B-/NR   California County Tobacco Securitization
                                  Agency Revenue, 5.125%, 6/1/38                      4,441,998
    1,450,000             NR/NR   California Enterprise Development Authority
                                  Recovery Zone Facility Revenue, 8.5%, 4/1/31        1,680,463
      568,006(b)          NR/NR   California Statewide Communities Development
                                  Authority Environmental Facilities Revenue,
                                  9.0%, 12/1/38                                           5,027
    4,000,000             BB/NR   California Statewide Communities Development
                                  Authority Revenue Higher Education Revenue,
                                  7.25%, 10/1/38 (144A)                               4,116,880
    5,150,000(a)        AA+/Aaa   Golden State Tobacco Securitization Corp.,
                                  Revenue Bonds, 7.8%, 6/1/42                         5,376,136
    7,000,000(a)        AA+/Aaa   Golden State Tobacco Securitization Corp.,
                                  Revenue Bonds, 7.875%, 6/1/42                       7,310,240
    7,885,000            AA-/WR   Lehman Municipal Trust Receipts Revenue,
                                  RIB, 10.829%, 9/20/28 (144A)                        9,995,263
    2,000,000           B-/Caa1   Tobacco Securitization Authority of Northern
                                  California, Revenue, 5.375%, 6/1/38                 1,694,820
    3,000,000            BB+/B3   Tobacco Securitization Authority of Southern
                                  California Revenue, 5.0%, 6/1/37                    2,555,310
                                                                                   ------------
                                                                                   $ 40,656,407
-----------------------------------------------------------------------------------------------
</TABLE>

The accompanying notes are an integral part of these financial statements.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 13

<PAGE>
Schedule of Investments | 10/31/12 (unaudited) (continued)

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------
 Principal
 Amount             S&P/Moody's
 USD ($)            Ratings                                                        Value
-----------------------------------------------------------------------------------------------
<S>                     <C>       <C>                                              <C>
                                  Colorado -- 1.0%
    2,000,000           BBB+/NR   Colorado Health Facilities Authority Revenue,
                                  5.25%, 5/15/42                                   $  2,065,900
    1,000,000             NR/NR   Kremmling Memorial Hospital District
                                  Certificate of Participation, 7.125%, 12/1/45       1,122,100
                                                                                   ------------
                                                                                   $  3,188,000
-----------------------------------------------------------------------------------------------
                                  Connecticut -- 6.0%
    1,000,000             NR/NR   Hamden Connecticut Facility Revenue,
                                  7.75%, 1/1/43                                    $  1,096,950
   10,335,000(c)         AAA/WR   Lehman Municipal Trust Receipts Revenue,
                                  11.545%, 8/21/35                                   13,915,457
    5,000,000              B/NR   Mohegan Tribe of Indians Gaming Authority,
                                  6.25%, 1/1/31                                       5,004,450
                                                                                   ------------
                                                                                   $ 20,016,857
-----------------------------------------------------------------------------------------------
                                  District of Colombia -- 3.6%
    5,000,000          BBB/Baa1   District of Columbia Tobacco Settlement
                                  Financing Corp., Revenue, 6.5%, 5/15/33          $  5,905,800
    6,000,000          BBB/Baa1   District of Columbia Tobacco Settlement
                                  Financing Corp., Revenue, 6.75%, 5/15/40            6,119,340
                                                                                   ------------
                                                                                   $ 12,025,140
-----------------------------------------------------------------------------------------------
                                  Florida -- 7.4%
    1,500,000             NR/NR   Alachua County Health Facilities Authority
                                  Revenue, 8.125%, 11/15/41                        $  1,746,045
    1,500,000             NR/NR   Alachua County Health Facilities Authority
                                  Revenue, 8.125%, 11/15/46                           1,746,045
    1,500,000             NR/NR   Beacon Lakes Community Development
                                  District Special Assessment, 6.9%, 5/1/35           1,531,380
     500,000             NR/Ba3   Capital Trust Agency Revenue Bonds,
                                  7.75%, 1/1/41                                         559,550
    1,000,000             NR/NR   Florida Development Finance Corp.,
                                  Educational Facilities Revenue, 6.0%,
                                  9/15/40                                             1,081,920
    2,000,000             NR/NR   Florida Development Finance Corp.,
                                  Educational Facilities Revenue, 7.625%,
                                  6/15/41                                             2,337,560
    1,000,000             NR/NR   Florida Development Finance Corp.,
                                  Educational Facilities Revenue, 7.75%,
                                  6/15/42                                             1,134,480
    1,000,000(a)          NR/WR   Hillsborough County Industrial Development
                                  Authority Revenue, 8.0%, 8/15/32                    1,420,040
    2,260,000             NR/NR   Liberty County Subordinate Revenue,
                                  8.25%, 7/1/28                                       2,291,663
    2,500,000              A/A2   Miami-Dade County Florida Aviation Revenue,
                                  5.5%, 10/1/41                                       2,855,825
</TABLE>

The accompanying notes are an integral part of these financial statements.

14 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------
 Principal
 Amount            S&P/Moody's
 USD ($)           Ratings                                                         Value
-----------------------------------------------------------------------------------------------
<S>                   <C>         <C>                                              <C>
                                  Florida -- (continued)
    1,000,000             NR/NR   St. Johns County Industrial Development
                                  Authority Revenue, 5.25%, 1/1/26                 $    960,430
    2,000,000             NR/NR   St. Johns County Industrial Development
                                  Authority Revenue, 5.375%, 1/1/40                   1,806,740
    5,000,000           NR/Baa1   Tallahassee Health Facilities Revenue,
                                  6.375%, 12/1/30                                     5,018,250
                                                                                   ------------
                                                                                   $ 24,489,928
-----------------------------------------------------------------------------------------------
                                  Georgia -- 2.7%
    4,240,000            AA-/WR   Atlanta Georgia Water and Wastewater
                                  Revenue, RIB, 10.829%, 1/30/13 (144A)            $  4,980,728
      500,000             B-/NR   Clayton County Development Authority
                                  Revenue, 9.0%, 6/1/35                                 558,730
    2,400,000             NR/NR   Fulton County Residential Care Facilities
                                  Revenue, 5.0%, 7/1/27                               2,394,888
    1,100,000             NR/NR   Fulton County Residential Care Facilities
                                  Revenue, 5.125%, 7/1/42                             1,058,178
                                                                                   ------------
                                                                                   $  8,992,524
-----------------------------------------------------------------------------------------------
                                  Idaho -- 1.5%
    5,000,000        BBB+/Baa1    Power County Industrial Development Corp.,
                                  Revenue, 6.45%, 8/1/32                           $  5,008,150
-----------------------------------------------------------------------------------------------
                                  Illinois -- 14.1%
    1,000,000(b)          NR/NR   Illinois Finance Authority Revenue, 6.0%,
                                  11/15/27                                         $    302,570
    3,865,000          BBB+/NR    Illinois Finance Authority Revenue, 6.0%,
                                  8/15/38                                             4,399,027
    2,000,000           AA+/Aa2   Illinois Finance Authority Revenue, 6.0%,
                                  8/15/39                                             2,351,180
    4,000,000(b)          NR/NR   Illinois Finance Authority Revenue, 6.0%,
                                  11/15/39                                            1,210,280
    2,450,000             NR/NR   Illinois Finance Authority Revenue, 6.375%,
                                  5/15/17                                             2,452,891
    2,500,000           NR/Baa2   Illinois Finance Authority Revenue, 6.5%,
                                  4/1/39                                              2,835,125
      500,000             NR/NR   Illinois Finance Authority Revenue, 7.0%,
                                  5/15/18                                               500,780
    1,700,000             NR/NR   Illinois Finance Authority Revenue, 7.625%,
                                  5/15/25                                             2,009,893
      600,000             NR/NR   Illinois Finance Authority Revenue, 7.75%,
                                  5/15/30                                               704,826
    2,000,000             NR/NR   Illinois Finance Authority Revenue, 8.0%,
                                  5/15/40                                             2,355,080
    3,200,000             NR/NR   Illinois Finance Authority Revenue, 8.0%,
                                  5/15/46                                             3,768,128
</TABLE>

The accompanying notes are an integral part of these financial statements.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 15
<PAGE>

Schedule of Investments | 10/31/12 (unaudited) (continued)

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------
 Principal
 Amount            S&P/Moody's
 USD ($)           Ratings                                                         Value
-----------------------------------------------------------------------------------------------
<S>                   <C>         <C>                                              <C>
                                  Illinois -- (continued)
    4,000,000             NR/NR   Illinois Finance Authority Revenue, 8.25%,
                                  5/15/45                                          $  4,291,280
    2,500,000             NR/NR   Illinois Finance Authority Revenue, 8.25%,
                                  2/15/46                                             2,723,200
   16,880,000(e)         AAA/A3   Metropolitan Pier & Exposition Authority
                                  Dedicated State Tax Revenue, 0.0%, 6/15/22         15,702,958
    1,515,000             NR/NR   Southwestern Illinois Development Authority
                                  Revenue, 5.625%, 11/1/26                            1,297,385
                                                                                   ------------
                                                                                   $ 46,904,603
-----------------------------------------------------------------------------------------------
                                  Indiana -- 1.6%
      250,000             NR/NR   City of Carmel Indiana Nursing Home
                                  Revenue, 7.0%, 11/15/32                          $    257,505
      750,000             NR/NR   City of Carmel Indiana Nursing Home
                                  Revenue, 7.125%, 11/15/42                             772,440
      500,000             NR/NR   City of Carmel Indiana Nursing Home
                                  Revenue, 7.125%, 11/15/47                             513,125
    3,570,000             NR/NR   Vigo County Hospital Authority Revenue,
                                  5.8%, 9/1/47 (144A)                                 3,694,415
                                                                                   ------------
                                                                                   $  5,237,485
-----------------------------------------------------------------------------------------------
                                  Louisiana -- 2.1%
    1,500,000         BBB-/Baa3   Louisiana Local Government Environmental
                                  Facilities & Community Development
                                  Authority Revenue, 6.75%, 11/1/32                $  1,688,160
    5,000,000           NR/Baa1   Louisiana Public Facilities Authority Revenue,
                                  5.5%, 5/15/47                                       5,282,200
                                                                                   ------------
                                                                                   $  6,970,360
-----------------------------------------------------------------------------------------------
                                  Maine -- 0.6%
    1,500,000           NR/Baa3   Maine Health & Higher Educational Facilities
                                  Authority Revenue, 7.5%, 7/1/32                  $  1,917,945
-----------------------------------------------------------------------------------------------
                                  Massachusetts -- 6.5%
    7,100,000              A/WR   Massachusetts Development Finance
                                  Agency Revenue, 5.75%, 1/1/42                    $  9,420,990
    2,250,000             NR/NR   Massachusetts Development Finance
                                  Agency Revenue, 7.1%, 7/1/32                        2,250,945
      825,000             AA/NR   Massachusetts Educational Financing
                                  Authority Revenue, 6.0%, 1/1/28                       959,796
    1,860,000           AAA/Aaa   Massachusetts Health & Educational
                                  Facilities Authority Revenue, 5.5%, 7/1/32          2,693,522
      940,000           NR/Baa2   Massachusetts Health & Educational
                                  Facilities Authority Revenue, 6.0%, 10/1/23           941,711
    4,500,000(b)          NR/NR   Massachusetts Health & Educational
                                  Facilities Authority Revenue, 6.5%, 1/15/38            23,040
</TABLE>

The accompanying notes are an integral part of these financial statements.

16 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------
 Principal
 Amount               S&P/Moody's
 USD ($)              Ratings                                                      Value
-----------------------------------------------------------------------------------------------
<S>                   <C>         <C>                                              <C>
                                  Massachusetts -- (continued)
    5,000,000            BB-/NR   Massachusetts Health & Educational
                                  Facilities Authority Revenue, 6.75%, 10/1/33     $  5,084,800
                                                                                   ------------
                                                                                   $ 21,374,804
-----------------------------------------------------------------------------------------------
                                  Michigan -- 3.3%
      935,000             NR/NR   Doctor Charles Drew Academy Certificate
                                  of Participation, 5.7%, 11/1/36                  $    682,943
    1,500,000            BB-/NR   John Tolfree Health System Corp.
                                  Revenue, 6.0%, 9/15/23                              1,499,880
    2,000,000            BB+/NR   Kent Hospital Finance Authority
                                  Revenue, 6.25%, 7/1/40                              2,099,700
    5,830,000             B-/NR   Michigan Tobacco Settlement Finance
                                  Authority Revenue, 6.0%, 6/1/48                     5,102,766
    1,410,000(a)         BBB/NR   Star International Academy Certificates
                                  of Participation, 6.125%, 3/1/37                    1,463,932
                                                                                   ------------
                                                                                   $ 10,849,221
-----------------------------------------------------------------------------------------------
                                  Minnesota -- 0.9%
    1,675,000            BB-/NR   Duluth Economic Development Authority
                                  Health Care Facilities Revenue, 7.25%,
                                  6/15/32                                          $  1,694,229
    1,000,000             NR/NR   Port Authority of the City of Bloomington,
                                  Recovery Zone Facility Revenue,
                                  9.0%, 12/1/35                                       1,196,590
                                                                                   ------------
                                                                                   $  2,890,819
-----------------------------------------------------------------------------------------------
                                  Montana -- 0.1%
    1,600,000(b)(d)       NR/NR   Two Rivers Authority Inc., Project Revenue,
                                  7.375%, 11/1/27                                  $    239,440
-----------------------------------------------------------------------------------------------
                                  Nevada -- 0.0%+
    2,000,000(b)(d)       NR/NR   Director of the State of Nevada Department
                                  of Business & Industry Transportation
                                  Revenue, 7.25%, 1/1/23                           $         20
-----------------------------------------------------------------------------------------------
                                  New Jersey -- 8.0%
    1,500,000             NR/NR   New Jersey Economic Development
                                  Authority Revenue, 10.5%, 6/1/32 (144A)          $  1,657,065
    5,000,000              B/B3   New Jersey Economic Development
                                  Authority Revenue, 5.25%, 9/15/29                   5,118,550
    2,500,000             B-/B3   New Jersey Economic Development
                                  Authority Revenue, 5.75%, 9/15/27                   2,545,425
    6,150,000              B/B3   New Jersey Economic Development
                                  Authority Revenue, 7.0%, 11/15/30                   6,172,878
    3,000,000             B-/B1   Tobacco Settlement Financing Corp.,
                                  Revenue, 4.625%, 6/1/26                             2,861,460
    8,000,000(a)       AA+/#Aaa   Tobacco Settlement Financing Corp.,
                                  Revenue, 6.75%, 6/1/39                              8,304,640
                                                                                   ------------
                                                                                   $ 26,660,018
-----------------------------------------------------------------------------------------------
</TABLE>

The accompanying notes are an integral part of these financial statements.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 17
<PAGE>

Schedule of Investments | 10/31/12 (unaudited) (continued)

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------
 Principal
 Amount            S&P/Moody's
 USD ($)           Ratings                                                         Value
-----------------------------------------------------------------------------------------------
<S>                   <C>         <C>                                              <C>
                                  New Mexico -- 1.2%
    1,500,000             NR/NR   Otero County New Mexico Project
                                  Revenue, 6.0%, 4/1/23                            $  1,372,110
    2,960,000             NR/NR   Otero County New Mexico Project
                                  Revenue, 6.0%, 4/1/28                               2,576,325
                                                                                   ------------
                                                                                   $  3,948,435
-----------------------------------------------------------------------------------------------
                                  New York -- 7.9%
    2,000,000             NR/NR   Chautauqua County Capital Resource
                                  Corp., Revenue, 8.0%, 11/15/30                   $  2,187,140
    3,000,000             NR/NR   Dutchess County Industrial Development
                                  Agency Revenue, 7.5%, 3/1/29                        3,085,770
    2,000,000           BBB+/NR   Hempstead Local Development Corp.
                                  Revenue, 5.75%, 7/1/39                              2,284,560
    2,000,000             BB/B2   New York City Industrial Development
                                  Agency Revenue, 5.25%, 12/1/32                      2,000,020
    2,000,000             BB/B2   New York City Industrial Development
                                  Agency Revenue, 7.625%, 12/1/32                     2,050,000
    7,040,000(c)         AAA/WR   New York State Dormitory Authority Revenue,
                                  13.073%, 5/29/14 (144A)                            10,545,709
    1,000,000            NR/Ba1   New York State Dormitory Authority
                                  Revenue, 6.125%, 12/1/29                            1,115,410
    3,000,000             NR/NR   Suffolk County Industrial Development
                                  Agency Revenue, 7.25%, 1/1/30                       3,002,730
                                                                                   ------------
                                                                                   $ 26,271,339
-----------------------------------------------------------------------------------------------
                                  North Carolina -- 2.8%
    4,795,000             NR/NR   Charlotte North Carolina Special Facilities
                                  Revenue, 7.75%, 2/1/28                           $  4,802,240
    4,785,000             NR/NR   Charlotte Special Facilities Revenue,
                                  5.6%, 7/1/27                                        4,464,788
                                                                                   ------------
                                                                                   $  9,267,028
-----------------------------------------------------------------------------------------------
                                  Oklahoma -- 0.4%
    1,225,000             NR/WR   Tulsa Municipal Airport Trust Revenue,
                                  6.25%, 6/1/20                                    $  1,228,063
-----------------------------------------------------------------------------------------------
                                  Pennsylvania -- 2.2%
    1,550,000           NR/Baa2   Allegheny County Hospital Development
                                  Authority Revenue, 5.125%, 5/1/25                $  1,550,481
    1,280,000(b)          NR/WR   Langhorne Manor Borough Higher Education
                                  Authority Revenue, 7.35%, 7/1/22                      371,174
    5,000,000           B-/Caa2   Pennsylvania Economic Development
                                  Financing Authority Solid Waste Disposal
                                  Revenue, 6.0%, 6/1/31                               4,974,750
</TABLE>

The accompanying notes are an integral part of these financial statements.

18 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------
 Principal
 Amount               S&P/Moody's
 USD ($)              Ratings                                                      Value
-----------------------------------------------------------------------------------------------
<S>                   <C>         <C>                                              <C>
                                  Pennsylvania -- (continued)
      500,000           BBB+/NR   Pennsylvania Higher Educational Facilities
                                  Authority Development Revenue, 5.4%,
                                  7/15/36                                          $    513,270
                                                                                   ------------
                                                                                   $  7,409,675
-----------------------------------------------------------------------------------------------
                                  Rhode Island -- 2.1%
    6,000,000(d)          NR/NR   Central Falls Rhode Island Detention
                                  Facility Corp., Revenue, 7.25%, 7/15/35          $  5,198,880
    1,500,000             NR/NR   Rhode Island Health & Educational
                                  Building Corp., Revenue, 8.375%, 1/1/46             1,764,270
                                                                                   ------------
                                                                                   $  6,963,150
-----------------------------------------------------------------------------------------------
                                  South Carolina -- 1.2%
    3,850,000(a)      BBB+/Baa1   South Carolina Jobs Economic Development
                                  Authority Revenue, 6.375%, 8/1/34                $  4,025,868
-----------------------------------------------------------------------------------------------
                                  Tennessee -- 1.5%
    4,600,000           BBB+/NR   Sullivan County Health, Educational &
                                  Housing Facilities Board Revenue,
                                  5.25%, 9/1/36                                    $  4,810,542
-----------------------------------------------------------------------------------------------
                                  Texas -- 16.9%
    1,345,000           NR/Caa2   Bexar County Housing Finance Corp., Multi
                                  Family Housing Revenue, 8.0%, 12/1/36            $    930,444
    2,500,000           BB+/Ba1   Central Texas Regional Mobility Authority
                                  Revenue, 6.75%, 1/1/41                              2,882,525
    4,000,000             NR/NR   Decatur Hospital Authority Medical
                                  Revenue, 7.0%, 9/1/25                               4,263,160
      725,078(b)(d)       NR/NR   Gulf Coast Industrial Development Authority
                                  Revenue, 7.0%, 12/1/36                                  6,707
    3,750,000             B-/B3   Houston Airport System Special Facilities
                                  Revenue, 5.7%, 7/15/29                              3,759,112
    3,000,000             NR/NR   Jefferson County Industrial Development
                                  Corp., Revenue, 8.25%, 7/1/32                       2,865,180
    5,340,000             NR/NR   Lubbock Health Facilities Development
                                  Corp., Nursing Home Revenue, 6.625%, 7/1/36         5,589,325
   10,000,000           BBB+/A3   North Texas Tollway Authority Transportation
                                  Revenue, 5.75%, 1/1/33                             11,084,400
    2,810,000(c)        AAA/Aaa   Northside Independent School District,
                                  GO, 11.408%, 9/29/12 (144A)                         3,340,781
    1,500,000             NR/NR   Red River Health Facilities Development
                                  Corp., Revenue, 8.0%, 11/15/41                      1,714,800
    3,000,000             NR/NR   Sanger Industrial Development Corp.,
                                  Revenue, 8.0%, 7/1/38                               3,013,890
    7,040,000(c)        AA+/Aaa   State of Texas, GO, 12.332%, 4/1/13                 9,039,078
</TABLE>

The accompanying notes are an integral part of these financial statements.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 19
<PAGE>

Schedule of Investments | 10/31/12 (unaudited) (continued)

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------
 Principal
 Amount               S&P/Moody's
 USD ($)              Ratings                                                      Value
-----------------------------------------------------------------------------------------------
<S>                   <C>         <C>                                              <C>
                                  Texas -- (continued)
    2,000,000             NR/NR   Tarrant County Cultural Education Facilities
                                  Finance Corp., Revenue, 8.0%, 11/15/34           $  2,267,080
    1,000,000             NR/NR   Tarrant County Cultural Education Facilities
                                  Finance Corp., Revenue, 8.125%, 11/15/39            1,116,870
    1,500,000             NR/NR   Tarrant County Cultural Education Facilities
                                  Finance Corp., Revenue, 8.25%, 11/15/44             1,681,365
    2,500,000             NR/NR   Travis County Health Facilities Development
                                  Corp., Revenue, 7.125%, 1/1/46                      2,631,850
                                                                                   ------------
                                                                                   $ 56,186,567
-----------------------------------------------------------------------------------------------
                                  Vermont -- 0.5%
    1,500,000(a)        A-/Baa1   Vermont Educational & Health Buildings
                                  Financing Agency Higher Education
                                  Revenue, 6.0%, 10/1/28                           $  1,577,775
-----------------------------------------------------------------------------------------------
                                  Virginia -- 0.3%
    1,000,000           BBB/Ba1   Peninsula Ports Authority Development
                                  Revenue, 6.0%, 4/1/33                            $  1,018,200
-----------------------------------------------------------------------------------------------
                                  Washington -- 9.9%
    4,710,000             A+/A2   Spokane Public Facilities District Hotel/Motel
                                  Tax & Sales, 5.75%, 12/1/27                      $  4,926,472
   14,315,000(e)        AA+/Aa1   State of Washington, GO, 0.0%, 6/1/22              11,295,537
    7,025,000          BBB/Baa1   Tobacco Settlement Authority Revenue,
                                  6.625%, 6/1/32                                      7,323,562
    3,795,000              A/A2   Washington State Health Care Facilities
                                  Authority Revenue, 6.0%, 1/1/33                     4,291,955
    5,000,000             NR/NR   Washington State Housing Finance
                                  Committee Nonprofit Revenue, 5.625%, 1/1/27         5,033,650
                                                                                   ------------
                                                                                   $ 32,871,176
-----------------------------------------------------------------------------------------------
                                  West Virginia -- 0.3%
      745,000             NR/NR   West Virginia Hospital Finance Authority
                                  Hospital Revenue, 9.125%, 10/1/41                $    919,449
-----------------------------------------------------------------------------------------------
                                  Wisconsin -- 1.8%
    2,320,000(f)          NR/NR   Aztalan Township, 7.5%, 5/1/18                   $         --
    2,500,000             NR/NR   Wisconsin Public Finance Authority
                                  Continuing Care Retirement Community
                                  Revenue, 8.25%, 6/1/46                              2,975,675
    1,500,000             NR/NR   Wisconsin State Public Finance Authority
                                  Revenue, 8.375%, 6/1/20                             1,516,665
    1,500,000             NR/NR   Wisconsin State Public Finance Authority
                                  Revenue, 8.625%, 6/1/47                             1,584,345
                                                                                   ------------
                                                                                   $  6,076,685
-----------------------------------------------------------------------------------------------
                                  TOTAL TAX EXEMPT OBLIGATIONS
                                  (Cost $368,859,838)                              $410,471,040
-----------------------------------------------------------------------------------------------
</TABLE>

The accompanying notes are an integral part of these financial statements.

20 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------------------
 Principal
 Amount             S&P/Moody's
 USD ($)            Ratings                                                        Value
--------------------------------------------------------------------------------------------------
<S>                       <C>     <C>                                              <C>
                                  MUNICIPAL COLLATERALIZED DEBT
                                  OBLIGATION -- 1.9% of Net Assets
   10,000,000(c)(d)       NR/NR   Non-Profit Preferred Funding Trust I, 6.75%,
                                  9/15/37 (144A)                                   $    6,316,500
--------------------------------------------------------------------------------------------------
                                  TOTAL MUNICIPAL COLLATERALIZED
                                  DEBT OBLIGATION
                                  (Cost $10,000,000)                               $    6,316,500
--------------------------------------------------------------------------------------------------
                                  TOTAL INVESTMENTS IN SECURITIES -- 125.7%
                                  (Cost -- $378,859,838) (g)(h)                    $  416,787,540
--------------------------------------------------------------------------------------------------
                                  OTHER ASSETS AND LIABILITIES -- 4.8%             $   15,908,220
--------------------------------------------------------------------------------------------------
                                  PREFERRED SHARES AT REDEMPTION VALUE,
                                  INCLUDING DIVIDENDS PAYABLE -- (30.5)%           $ (101,003,500)
--------------------------------------------------------------------------------------------------
                                  NET ASSETS APPLICABLE TO COMMON
                                  SHAREOWNERS -- 100.0%                            $  331,692,260
==================================================================================================
</TABLE>

+        Amount rounds to less than 0.1%.

NR       Security not rated by S&P or Moody's.

WR       Rating withdrawn by either 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
         October 31, 2012, the value of these securities amounted to
         $44,647,341, or 13.5% of total net assets applicable to common
         shareowners.

RIB      Residual Interest Bond. The interest rate is subject to change
         periodically and inversely based upon prevailing market rates. The
         interest rate shown is the rate at October 31, 2012.

GO       General Obligation.

(a)      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.

(b)      Security is in default and is non income producing.

(c)      The interest rate is subject to change periodically. The interest is
         shown is the rate at October 31, 2012.

(d)      Indicates a security that has been deemed as illiquid. The aggregate
         cost of illiquid securities is $20,088,607. The aggregate fair value of
         $11,761,547 represents 3.5% of total net assets applicable to common
         shareowners.

(e)      Security issued with a zero coupon. Income is recognized through
         accretion of discount.

(f)      Security is valued using fair value methods (other than prices
         supplied by independent pricing services). (See Note 1A).

The accompanying notes are an integral part of these financial statements.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 21
<PAGE>

Schedule of Investments | 10/31/12 (unaudited) (continued)

(g)    The concentration of investments by type of obligation/ market
       sector is as follows:

<TABLE>
<CAPTION>
<S>                                                                       <C>
    Insured
      NATL-RE                                                               4.9%
      FSA                                                                   3.6
      NATL-RE FGIC                                                          2.7
      AMBAC GO OF INSTN                                                     2.3
      PSF-GTD                                                               0.8
      GO OF INSTN                                                           0.6
    Revenue Bonds:
      Health Revenue                                                       17.0
      Other Revenue                                                        16.2
      Facilities Revenue                                                   13.9
      Tobacco Revenue                                                      13.7
      Development Revenue                                                   8.0
      Education Revenue                                                     6.2
      Airport Revenue                                                       5.6
      Transportation Revenue                                                2.7
      Pollution Control Revenue                                             1.8
      Utilities Revenue                                                     0.0*
                                                                          ------
                                                                          100.0%
                                                                          ======
</TABLE>

*   Amount is less than 0.1%

(h) At October 31, 2012, the net unrealized gain on investments based on cost
    for federal tax purposes of $379,124,230 was as follows:

<TABLE>
<CAPTION>
<S>                                                                       <C>
    Aggregate gross unrealized gain for all investments in which
       there is an excess of value over tax cost                          $ 52,631,449

    Aggregate gross unrealized loss for all investments in which
       there is an excess of tax cost over value                           (14,968,139)
                                                                          ------------
    Net unrealized gain                                                   $ 37,663,310
                                                                          ============
</TABLE>

For financial reporting purposes net unrealized gain on investments was
$37,927,702 and the cost of investments aggregated was $378,859,838.

Purchases and sales of securities (excluding temporary cash investments) for the
six months ended October 31, 2012 aggregated $26,147,981 and $16,836,658,
respectively.

The accompanying notes are an integral part of these financial statements.

22 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

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. See Notes to Financial Statements -- Note 1A

The following is a summary of the inputs used as of October 31, 2012, in valuing
the Trust's investments.

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------
                                             Level 1    Level 2         Level 3    Total
-----------------------------------------------------------------------------------------------
<S>                                          <C>        <C>             <C>        <C>
 Tax exempt obligations:                     $ --       $410,471,040    $ --       $410,471,040
 Municipal collateralized debt obligation:     --          6,316,500      --          6,316,500
-----------------------------------------------------------------------------------------------
 Total                                       $ --       $416,787,540    $ --       $416,787,540
===============================================================================================
</TABLE>

The following is a reconciliation of assets valued using significant
unobservable inputs (level 3):

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------------------
                                  Change in
             Balance   Realized   Unrealized                            Accrued      Transfers  Transfers  Balance
             as of     gain       appreciation                          discounts/   in to      out of     as of
             3/31/12   (loss)     (depreciation)  Purchases   Sales     premiums     Level 3*   Level 3*   10/31/12
-------------------------------------------------------------------------------------------------------------------
<S>          <C>       <C>        <C>             <C>         <C>       <C>          <C>        <C>        <C>
Tax exempt
 obligations $ --      $ --       $ --            $ --        $ --      $ --         $ --       $ --       $ --**
-------------------------------------------------------------------------------------------------------------------
Total        $ --      $ --       $ --            $ --        $ --      $ --         $ --       $ --       $ --**
===================================================================================================================
</TABLE>

*   Transfers are calculated on the beginning of period values.

**  Azatlan Township is fair valued at $0.

During the six months ended October 31, 2012, there were no transfers between
Levels 1, 2 and 3.

The accompanying notes are an integral part of these financial statements.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 23
<PAGE>

Statement of Assets and Liabilities | 10/31/12 (unaudited)

<TABLE>
<CAPTION>
<S>                                                                <C>
ASSETS:
  Investments in securities, at value (cost $378,859,838)          $416,787,540
  Cash                                                                5,115,032
  Receivables --
     Investment securities sold                                       2,000,000
     Interest receivable                                              9,071,637
  Reinvestment of distributions                                          84,667
  Prepaid expenses                                                       12,482
  Other assets                                                           22,500
--------------------------------------------------------------------------------
        Total assets                                               $433,093,858
--------------------------------------------------------------------------------
LIABILITIES:
   Due to affiliates                                               $    234,050
   Administration fee payable                                            61,985
   Accrued expenses                                                     102,063
--------------------------------------------------------------------------------
         Total liabilities                                         $    398,098
--------------------------------------------------------------------------------
PREFERRED SHARES AT REDEMPTION VALUE:
  $25,000 liquidation value per share applicable to 4,040 shares,
     including dividends payable of $3,500                         $101,003,500
--------------------------------------------------------------------------------
NET ASSETS APPLICABLE TO COMMON SHAREOWNERS:
  Paid-in capital                                                  $320,777,492
  Undistributed net investment income                                10,287,974
  Accumulated net realized loss on investments                      (37,300,908)
  Net unrealized gain on investments                                 37,927,702
--------------------------------------------------------------------------------
        Net assets applicable to common shareowners                $331,692,260
================================================================================
NET ASSET VALUE PER COMMON SHARE:
No par value (unlimited number of shares authorized)
  Based on $331,692,260/22,530,811 common shares                   $      14.72
================================================================================
</TABLE>

The accompanying notes are an integral part of these financial statements.

24 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

Statement of Operations (unaudited)

For the six months ended 10/31/12

<TABLE>
<CAPTION>
<S>                                                                <C>             <C>
INVESTMENT INCOME:
   Interest                                                                        $ 17,263,623
-----------------------------------------------------------------------------------------------

EXPENSES:
  Management fees                                                  $  1,291,038
  Administration fees                                                   103,276
  Transfer agent fees and expenses                                       13,621
  Shareholder communications expense                                      5,743
  Auction agent fees                                                    127,090
  Custodian fees                                                          3,535
  Registration fees                                                      11,977
  Professional fees                                                      49,910
  Printing expenses                                                      16,749
  Trustees' fees                                                          6,894
  Pricing fees                                                            4,357
  Miscellaneous                                                          30,665
-----------------------------------------------------------------------------------------------
     Total expenses                                                                $  1,664,855
-----------------------------------------------------------------------------------------------
         Net investment income                                                     $ 15,598,768
-----------------------------------------------------------------------------------------------
REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS:
   Net realized loss on investments                                $ (3,910,000)
   Change in net unrealized gain on Investments                    $ 15,045,126
-----------------------------------------------------------------------------------------------
      Net gain on investments                                                      $ 11,135,126
-----------------------------------------------------------------------------------------------
DISTRIBUTIONS TO PREFERRED SHAREOWNERS FROM
NET INVESTMENT INCOME:                                                             $   (385,559)
-----------------------------------------------------------------------------------------------
   Net increase in net assets applicable to common shareowners
      resulting from operations                                                    $ 26,348,335
===============================================================================================
</TABLE>

The accompanying notes are an integral part of these financial statements.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 25
<PAGE>

Statements of Changes in Net Assets (unaudited)

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------------------
                                                               Six Months
                                                               Ended               Year
                                                               10/30/12            Ended
                                                               (unaudited)         4/30/12
--------------------------------------------------------------------------------------------------
<S>                                                            <C>                 <C>
FROM OPERATIONS:
Net investment income                                          $  15,598,768       $   23,022,348
Net realized loss on investments                                  (3,910,000)          (8,740,047)
Change in net unrealized gain (loss) on investments               15,045,126           37,817,446
Distributions to preferred shareowners from net
   investment income                                                (385,559)            (234,733)
--------------------------------------------------------------------------------------------------
       Net increase in net assets applicable to common
          shareowners resulting from operations                $  26,348,335       $   51,865,014
--------------------------------------------------------------------------------------------------
DISTRIBUTIONS TO COMMON SHAREOWNERS:
Net investment income ($0.570 and $1.197 per share,
   respectively)                                               $ (12,831,067)      $  (26,857,057)
--------------------------------------------------------------------------------------------------
         Total distributions to common shareowners             $ (12,831,067)      $  (26,857,057)
--------------------------------------------------------------------------------------------------
FROM TRUST SHARE TRANSACTIONS:
Conversion                                                     $       7,340       $           --
Reinvestment of distributions                                  $     537,092       $    1,569,243
--------------------------------------------------------------------------------------------------
   Net increase in net assets applicable to common
      shareowners from Trust share transactions                $     544,432       $    1,569,243
--------------------------------------------------------------------------------------------------
   Net increase in net assets applicable to
      common shareowners                                       $  14,061,700       $   26,577,200
NET ASSETS APPLICABLE TO COMMON SHAREOWNERS:
Beginning of period                                              317,630,560          291,053,360
--------------------------------------------------------------------------------------------------
End of period                                                  $ 331,692,260       $  317,630,560
--------------------------------------------------------------------------------------------------
Undistributed net investment income                            $  10,287,974       $    7,905,832
==================================================================================================
</TABLE>

The accompanying notes are an integral part of these financial statements.

26 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

Financial Highlights

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------------------------------------------
                                                               Six Months
                                                               Ended       Year     Year      Year     Year       Year
                                                               10/31/12    Ended    Ended     Ended    Ended      Ended
                                                               (unaudited) 4/30/12  4/30/11   4/30/10  4/30/09    4/30/08
---------------------------------------------------------------------------------------------------------------------------
<S>                                                            <C>         <C>      <C>       <C>      <C>        <C>
Per Share Operating Performance
Net asset value, beginning of period                           $14.12      $13.00   $ 13.86   $11.18   $ 14.07    $ 16.02
---------------------------------------------------------------------------------------------------------------------------
Increase (decrease) from investment operations: (a)
   Net investment income                                       $ 0.69      $ 1.03   $  1.12   $ 1.17   $  1.12    $  1.08
   Net realized and unrealized gain (loss) on investments and
      interest rate swaps                                        0.50        1.30     (0.89)    2.50     (3.05)     (2.03)
Distributions to preferred shareowners from:
   Net investment income                                        (0.02)      (0.01)    (0.02)   (0.02)    (0.11)     (0.17)
---------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) from investment operations             $ 1.17      $ 2.32   $  0.21   $ 3.65   $ (2.04)   $ (1.12)
---------------------------------------------------------------------------------------------------------------------------
Distributions to common shareowners from:
   Net investment income                                        (0.57)      (1.20)    (1.07)   (0.97)    (0.85)     (0.83)
---------------------------------------------------------------------------------------------------------------------------
Net increase (decrease) in net asset value                     $ 0.60      $ 1.12   $ (0.86)  $ 2.68   $ (2.89)   $ (1.95)
---------------------------------------------------------------------------------------------------------------------------
Net asset value, end of period (b)                             $14.72      $14.12   $ 13.00   $13.86   $ 11.18    $ 14.07
---------------------------------------------------------------------------------------------------------------------------
Market value, end of period (b)                                $16.04      $15.49   $ 13.40   $14.34   $ 10.40    $ 13.88
===========================================================================================================================
Total return at market value (c)                                 7.53%      25.95%     1.04%   48.69%   (18.85)%    (2.28)%
Ratios to average net assets of common shareowners:
   Net expenses (d)                                              1.01%(e)    1.08%     1.12%    1.14%     1.19%      1.03%
   Net investment income before preferred share distributions    9.50%(e)    7.50%     8.26%    9.07%     9.36%      7.17%
   Preferred share distributions                                 0.23%(e)    0.08%     0.14%    0.16%     0.95%      1.13%
   Net investment income available to common shareowners         9.27%(e)    7.42%     8.12%    8.91%     8.41%      6.04%
</TABLE>

The accompanying notes are an integral part of these financial statements.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 27
<PAGE>

Financial Highlights (continued)

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------------------------------------
                                                                     Six Months
                                                                     Ended        Year      Year      Year      Year      Year
                                                                     10/31/12     Ended     Ended     Ended     Ended     Ended
                                                                     (Unaudited)  4/30/12   4/30/11   4/30/10   4/30/09   4/30/08
------------------------------------------------------------------------------------------------------------------------------------
<S>                                                                  <C>          <C>       <C>       <C>       <C>       <C>
Portfolio turnover                                                          4%          11%       10%       11%       16%       17%
Net assets of common shareowners, end of period (in thousands)       $331,692     $317,631  $291,053  $308,456  $247,560  $311,231
Preferred shares outstanding (in thousands)                          $100,997     $101,000  $101,000  $101,000  $101,000  $101,000
Asset coverage per preferred share, end of period                    $107,100     $103,623  $ 97,044  $101,351  $ 86,278  $102,047
Average market value per preferred share (f)                         $ 24,999     $ 25,000  $ 25,000  $ 25,000  $ 25,000  $ 25,000
Liquidation value, including dividends payable, per preferred share  $ 24,998     $ 25,001  $ 25,001  $ 25,001  $ 25,001  $ 25,010
Ratios to average net assets of common shareowners before
   waivers and reimbursement of expenses
   Net expenses (d)                                                      1.01%(e)     1.08%     1.12%     1.14%     1.19%     1.03%
   Net investment income before preferred share distributions            9.50%(e)     7.50%     8.26%     9.07%     9.36%     7.17%
   Preferred share distributions                                         0.23%(e)     0.08%     0.14%     0.16%     0.95%     1.13%
   Net investment income available to common shareowners                 9.27%(e)     7.42%     8.12%     8.91%     8.41%     6.04%
====================================================================================================================================
</TABLE>

(a) The per common share data presented above is based upon the average common
    shares outstanding for the periods presented.

(b) Net asset value and market value are published in Barron's on Saturday, The
    Wall Street Journal on Monday and The New York Times on Monday and Saturday.

(c) Total investment return is calculated assuming a purchase of common shares
    at the current market value on the first day and a sale at the current
    market value on the last day of the periods reported. Dividends and
    distributions, if any, are assumed for purposes of this calculation to be
    reinvested at prices obtained under the Trust's dividend reinvestment plan.
    Total investment return does not reflect brokerage commissions. Past
    performance is not a guarantee of future results.

(d) Expense ratios do not reflect the effect of distribution payments to
    preferred shareowners.

(e) Annualized.

(f) Market value is redemption value without an active market.

The information above represents the audited operating performance data for a
share of common stock outstanding, total investment return, ratios to average
net assets and other supplemental data for the periods indicated. This
information has been determined based upon financial information provided in the
financial statements and market value data for the Trust's common shares.

The accompanying notes are an integral part of these financial statements.

28 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

Notes to Financial Statements | 10/31/12 (unaudited)

1. Organization and Significant Accounting Policies

Pioneer Municipal High Income Trust (the Trust) was organized as a Delaware
statutory trust on March 13, 2003. Prior to commencing operations on July 21,
2003, the Trust had no operations other than matters relating to its
organization and registration as a diversified, closed-end management investment
company under the Investment Company Act of 1940, as amended. The investment
objective of the Trust is to seek a high level of current income exempt from
regular federal income tax, and the Trust may, as a secondary objective, also
seek capital appreciation to the extent that it is consistent with its primary
investment objective.

The Trust's financial statements have been prepared in conformity with U.S.
generally accepted accounting principles that require the management of the
Trust to, among other things, make estimates and assumptions that affect the
reported amounts of assets and liabilities, the disclosure of contingent assets
and liabilities at the date of the financial statements, and the reported
amounts of income, expenses, and gain or loss on investments during the
reporting year. Actual results could differ from those estimates.

The following is a summary of significant accounting policies followed by the
Trust in the preparation of its financial statements, which are consistent with
those policies generally accepted in the investment company industry:

A.  Security Valuation

    Security transactions are recorded as of trade date. Fixed income securities
    with remaining maturity of more than sixty days are valued at prices
    supplied by independent pricing services, which consider such factors as
    market prices, market events, quotations from one or more brokers, Treasury
    spreads, yields, maturities and ratings. Valuations may be supplemented by
    dealers and other sources, as required. The values of interest rate swaps
    are determined by obtaining dealer quotations. Equity securities that have
    traded on an exchange are valued at the last sale price on the principal
    exchange where they are traded. Equity securities that have not traded on
    the date of valuation, or securities for which sale prices are not
    available, generally are valued using the mean between the last bid and
    asked prices. Short-term fixed income securities with remaining maturities
    of sixty days or less generally are valued at amortized cost. Money market
    mutual funds are valued at net asset value.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 29
<PAGE>

    Securities for which independent pricing services are unable to supply
    prices or for which market prices and/or quotations are not readily
    available or are considered to be unreliable are valued using fair value
    methods pursuant to procedures adopted by the Board of Trustees. The Trust
    may use fair value methods if it is determined that a significant event has
    occurred after the close of the exchange or market on which the security
    trades and prior to the determination of the Trust's net asset value.
    Examples of a significant event might include political or economic news,
    corporate restructurings, natural disasters, terrorist activity or trading
    halts. Thus, the valuation of the Trust's securities may differ from
    exchange prices.

    At October 31, 2012, one security was valued using fair value methods (in
    addition to securities valued using prices supplied by independent pricing
    services) representing 0.0% of net assets. Inputs used when applying fair
    value methods to value a security may include credit ratings, the financial
    condition of the company, current market conditions and comparable
    securities.

    Discount and premium on debt securities are accreted or amortized,
    respectively, daily into interest income on a yield-to-maturity basis with a
    corresponding increase or decrease in the cost basis of the security.
    Interest income, including income bearing cash accounts, is recorded on an
    accrual basis.

    Dividend income is recorded on the ex-dividend date, except that certain
    dividends from foreign securities where the ex-dividend date may have passed
    are recorded as soon as the Trust becomes aware of the ex-dividend data in
    the exercise of reasonable diligence.

    Gains and losses on sales of investments are calculated on the identified
    cost method for both financial reporting and federal income tax purposes.

B.  Federal Income Taxes

    It is the Trust's policy to comply with the requirements of the Internal
    Revenue Code applicable to regulated investment companies and to distribute
    all of its taxable income and net realized capital gains, if any, to its
    shareowners. Therefore, no federal income tax provision is required. Tax
    years for the prior three fiscal years remain subject to examination by
    federal and state tax authorities.

    The amounts and characterizations of distributions to shareowners for
    financial reporting purposes are determined in accordance with federal
    income tax rules. Therefore, the sources of the Trust's distributions may be
    shown in the accompanying financial statements as from or in excess of net
    investment income or as from net realized gain (loss) on investment
    transactions, or as from paid-in capital, depending on the type of book/tax
    differences that may exist.

30 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

    The tax character of current year distributions payable to common and
    preferred shareowners will be determined at the end of the current taxable
    year. The tax character of distributions paid during the year ended April
    30, 2012 was as follows:

    <TABLE>
    <CAPTION>
    ----------------------------------------------------------------------------
                                                                            2012
    ----------------------------------------------------------------------------
    <S>                                                              <C>
    Distribution paid from:
    Tax-exempt income                                                $25,801,273
    Ordinary income                                                    1,290,517
    ----------------------------------------------------------------------------
      Total taxable distribution                                     $27,091,790
    ============================================================================
    </TABLE>

    The following shows the components of distributable earnings (losses) on a
    federal income tax basis at April 30, 2012:

    <TABLE>
    <CAPTION>
    ----------------------------------------------------------------------------
                                                                           2012
    ----------------------------------------------------------------------------
    <S>                                                             <C>
    Distributable earnings:
    Undistributed tax-exempt income                                 $ 8,944,200
    Undistributed ordinary income                                       137,848
    Capital loss carryforward                                       (25,495,311)
    Post-October loss deferred                                       (8,801,617)
    Dividends payable                                                    (5,804)
    Unrealized appreciation                                          22,618,184
    ----------------------------------------------------------------------------
       Total                                                       $ (2,602,500)
    ============================================================================
    </TABLE>

    The difference between book-basis and tax-basis unrealized depreciation is
    primarily attributable to the difference between book and tax amortization
    methods for premiums and discounts on fixed income securities, book/tax
    difference in the accrual of income on securities in default, the deferral
    of post-October capital losses for tax purposes and other temporary
    differences.

C.  Automatic Dividend Reinvestment Plan

    All common shareowners whose shares are registered in their own names
    automatically participate in the Automatic Dividend Reinvestment Plan (the
    Plan), under which participants receive all dividends and capital gain
    distributions (collectively, dividends) in full and fractional common shares
    of the Trust in lieu of cash. Shareowners may elect not to participate in
    the Plan. Shareowners not participating in the Plan receive all dividends
    and capital gain distributions in cash. Participation in the Plan is
    completely voluntary and may be terminated or resumed at any time without
    penalty by notifying American Stock Transfer & Trust Company, the agent for
    shareowners in administering the Plan (the Plan Agent), in writing prior to
    any dividend record date; otherwise such termination or resumption will be
    effective with respect to any subsequently declared dividend or other
    distribution.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 31
<PAGE>

    If a shareowner's shares are held in the name of a brokerage firm, bank or
    other nominee, the shareowner can ask the firm or nominee to participate in
    the Plan on the shareowner's behalf. If the firm or nominee does not offer
    the Plan, dividends will be paid in cash to the shareowner of record. A firm
    or nominee may reinvest a shareowner's cash dividends in common shares of
    the Trust on terms that differ from the terms of the Plan.

    Whenever the Trust declares a dividend on common shares payable in cash,
    participants in the Plan will receive the equivalent in common shares
    acquired by the Plan Agent either (i) through receipt of additional unissued
    but authorized common shares from the Trust or (ii) by purchase of
    outstanding common shares on the New York Stock Exchange or elsewhere. If,
    on the payment date for any dividend, the net asset value per common share
    is equal to or less than the market price per share plus estimated brokerage
    trading fees (market premium), the Plan Agent will invest the dividend
    amount in newly issued common shares. The number of newly issued common
    shares to be credited to each account will be determined by dividing the
    dollar amount of the dividend by the net asset value per common share on the
    date the shares are issued, provided that the maximum discount from the then
    current market price per share on the date of issuance does not exceed 5%.
    If, on the payment date for any dividend, the net asset value per common
    share is greater than the market value (market discount), the Plan Agent
    will invest the dividend amount in common shares acquired in open-market
    purchases. There are no brokerage charges with respect to newly issued
    common shares. However, each participant will pay a pro rata share of
    brokerage trading fees incurred with respect to the Plan Agent's open-market
    purchases. Participating in the Plan does not relieve shareowners from any
    federal, state or local taxes which may be due on dividends paid in any
    taxable year. Shareowners holding Plan shares in a brokerage account may not
    be able to transfer the shares to another broker and continue to participate
    in the Plan.

D.  Risks

    At times, the Trust's investments may represent industries or industry
    sectors that are interrelated or have common risks, making the Trust more
    susceptible to any economic, political, or regulatory developments or other
    risks affecting those industries and sectors. Information regarding the
    Trust's principal risks is contained in the Trust's original offering
    prospectus, with additional information included in the Trust's shareowner
    reports issued from time to time. Please refer to those documents when
    considering the Trust's principal risks.

32 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

    The Trust may invest in both investment grade and below investment grade
    (high-yield) municipal securities with a broad range of maturities and
    credit ratings. Debt securities rated below investment grade are commonly
    referred to as "junk bonds" and are considered speculative. These securities
    involve greater risk of loss, are subject to greater price volatility, and
    are less liquid, especially during periods of economic uncertainty or
    change, than higher rated debt securities.

2. Management Agreement

Pioneer Investment Management, Inc. (PIM), the Trust's investment adviser, a
wholly owned indirect subsidiary of UniCredit S.p.A. (UniCredit), manages the
Trust's portfolio. Management fees payable under the Trust's Advisory Agreement
with PIM are calculated daily at the annual rate of 0.60% of the Trust's average
daily managed assets. "Managed assets" means (a) the total assets of the Trust,
including any form of investment leverage, minus (b) all accrued liabilities
incurred in the normal course of operations, which shall not include any
liabilities or obligations attributable to investment leverage obtained through
(i) indebtedness of any type (including, without limitation, borrowing through a
credit facility of the issuance of debt securities), (ii) the issuance of
preferred stock or other similar preference securities, and/or (iii) any other
means. For the six months ended October 31, 2012, the net management fee was
0.60% of the Trust's average daily managed assets, which was equivalent to 0.80%
of the Trust's average daily net assets attributable to the common shareowners.

In addition, under PIM's management and administration agreements, certain other
services and costs are paid by PIM and reimbursed by the Trust. At October 31,
2012, $296,035 was payable to PIM related to management costs, administrative
costs and certain other reimbursements and is included in "Due to affiliates"
and "Administration fee" on the Statement of Assets and Liabilities.

Effective May 1, 2012, PIM has retained Brown Brothers Harriman & Company (BBH)
to provide certain administrative and accounting services to the Trust on its
behalf. For such services, PIM pays BBH a monthly fee at an annual rate of
0.025% of the Trust's average daily managed assets subject to a minimum monthly
fee of $6,250. Previously, PIM had retained State Street Bank & Trust Company
(State Street) to provide such services. PIM paid State Street a monthly fee at
an annual rate of 0.07% of the Trust's average daily managed assets up to $500
million, subject to a minimum monthly fee of $10,000. Neither BBH nor State
Street received compensation directly from the Trust for providing such
services.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 33
<PAGE>

3. Transfer Agents

Pioneer Investment Management Shareholder Services, Inc. (PIMSS), a wholly owned
indirect subsidiary of UniCredit, through a sub-transfer agency agreement with
American Stock Transfer & Trust Company, provides substantially all transfer
agent and shareowner services related to the Trust's common shares at negotiated
rates. Deutsche Bank Trust Company Americas (Deutsche Bank) is the transfer
agent, registrar, dividend paying agent and auction agent with respect to the
Trust's Auction Preferred Shares (APS). The Trust pays Deutsche Bank an annual
fee, as is agreed to from time to time by the Trust and Deutsche Bank, for
providing such services.

In addition, the Trust reimburses PIMSS for out-of-pocket expenses incurred by
PIMSS related to shareowner communications activities such as proxy and
statement mailings and outgoing phone calls.

4. Expense Offset Agreements

The Trust has entered into an arrangement with its custodian whereby credits
realized as a result of uninvested cash balances are used to reduce a portion of
the Trust's custodian expenses. For the six months ended October 31, 2012, the
Trust expenses were not reduced under such arrangement.

5. Interest Rate Swaps

The Trust may enter into interest rate swap transactions to attempt to protect
itself from increasing dividend or interest expense on its leverage resulting
from increasing short-term interest rates. The cost of leverage may rise with an
increase in interest rates, generally having the effect of lower yields and
potentially lower dividends to common shareowners. Interest rate swaps can be
used to "lock in" the cost of leverage and reduce the negative impact that
rising short-term interest rates would have on the Trust's leveraging costs.

An interest rate swap is an agreement between two parties, which involves
exchanging floating rate and fixed rate interest payments for a specified period
of time. Interest rate swaps involve the accrual of the net interest payments
between the parties on a daily basis, with the net amount recorded within the
unrealized appreciation/depreciation of interest rate swaps on the Statement of
Assets and Liabilities. Once the interim payments are settled in cash, at the
pre-determined dates specified in the agreement, the net amount is recorded as
realized gain or loss from interest rate swaps on the Statement of Operations.
During the term of the swap, changes in the value of the swap are recognized as
unrealized gains and losses by "marking-to-market" the value of the swap based
on values obtained from dealer quotations. When the swap is terminated, the
Trust will record a realized gain or loss equal to the difference, if any,
between the proceeds from (or cost of) closing the contract and the cost basis
of the contract. The Trust is exposed to credit risk in the

34 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

event of non-performance by the other party to the interest rate swap. Risk may
also arise with regard to market movements in the value of the swap arrangement
that do not exactly offset the changes in the related dividend requirement or
interest expense on the Trust's leverage.

There were no interest rate swap contracts open during the six months ended
October 31, 2012 or outstanding at October 31, 2012.

6. Trust Shares

There are an unlimited number of common shares of beneficial interest
authorized.

Transactions in common shares of beneficial interest for the six months ended
October 31, 2012 and the year ended April 30, 2012 were as follows:

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
                                                           10/31/12      4/30/12
--------------------------------------------------------------------------------
<S>                                                      <C>          <C>
 Shares outstanding at beginning of period               22,495,129   22,381,423
 Reinvestment of distributions                               35,682      113,706
--------------------------------------------------------------------------------
 Shares outstanding at end of period                     22,530,811   22,495,129
================================================================================
</TABLE>

The Trust may classify or reclassify any unissued shares of beneficial interest
into one or more series of preferred shares of beneficial interest. As of
October 31, 2012, there were 4,040 APS as follows: Series A-2,000 and Series
B-2,040.

Dividends on Series A and Series B are cumulative at a rate which is to be reset
every seven days based on the results of an auction. An auction fails if there
are more APS offered for sale than there are buyers. When an auction fails, the
dividend rate for the period will be the maximum rate on the auction dates
described in the prospectus for the APS. Preferred shareowners are not able to
sell their APS at an auction if the auction fails. Since February 2008, the
Trust's auctions related to the APS have failed. The maximum rate for each
series is 110% of the 7 day commercial paper rate or adjusted Kenny rate.
Dividend rates on APS ranged from 0.278% to 0.364% during the six months ended
October 31, 2012.

The Trust may not declare dividends or make other distributions on its common
shares or purchase any such shares if, at the time of the declaration,
distribution or purchase, the Trust does not comply with the asset coverage
ratios described in the prospectus for the APS.

The APS are redeemable at the option of the Trust, in whole or in part, on any
dividend payment date at $25,000 per share plus any accumulated or unpaid
dividends, whether or not declared. The APS are also subject to mandatory
redemption at $25,000 per share plus any accumulated or unpaid dividends,

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 35
<PAGE>

whether or not declared, if certain requirements relating to the composition of
the assets and liabilities of the Trust as set forth in the Statement of
Preferences are not satisfied.

The holders of APS have voting rights equal to the holders of the Trust's common
shares (one vote per share) and will vote together with holders of the common
shares as a single class. Holders of APS are also entitled to elect two of the
Trust's Trustees. In addition, the Investment Company Act of 1940, as amended,
requires that along with approval by shareowners that might otherwise be
required, the approval of the holders of a majority of any outstanding preferred
shares, voting separately as a class, would be required to (a) adopt any plan of
reorganization that would adversely affect the preferred shares and (b) take any
action requiring a vote of security holders, including, among other things,
changes in the Trust's subclassification as a closed-end management investment
company or changes in its fundamental investment restrictions.

7. Subsequent Events

The Board of Trustees of the Trust declared on November 5, 2012 a dividend from
undistributed net investment income of $0.095 per common share payable November
30, 2012, to common shareowners of record on November 16, 2012.

Subsequent to October 31, 2012, dividends declared and paid on preferred shares
totaled $15,545 in aggregate for the two outstanding preferred share series
through November 19, 2012.

Results of Shareholder Meeting (unaudited)

At the annual meeting of shareowners held on September 18, 2012, shareowners of
Pioneer Municipal High Income Trust were asked to consider the proposal
described below. A report of the total votes cast by the Trust's shareholders
follows:

Proposal 1 -- To elect Class III Trustees.

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------
 Nominee                                      For                  Withheld
--------------------------------------------------------------------------------
<S>                                           <C>                  <C>
 Thomas J. Perna                              19,189,584.943       557,728.569
 Marguerite A. Piret*                              2,557.000            69.000
</TABLE>

*   Elected by preferred shares only.

36 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

Trustees, Officers and Service Providers

Trustees                               Officers
Thomas J. Perna, Chairman              John F. Cogan, Jr., President*
David R. Bock                          Daniel K. Kingsbury, Executive
John F. Cogan, Jr.                        Vice President
Benjamin M. Friedman                   Mark E. Bradley, Treasurer**
Margaret B.W. Graham                   Christopher J. Kelley, Secretary
Daniel K. Kingsbury
Marguerite A. Piret
Stephen K. West

Investment Adviser and Administrator
Pioneer Investment Management, Inc.

Custodian and Sub-Administrator
Brown Brothers Harriman & Co.

Legal Counsel
Bingham McCutchen LLP

Transfer Agent
Pioneer Investment Management Shareholder Services, Inc

Shareowner Services and Transfer Agent
American Stock Transfer & Trust Company

Proxy Voting Policies and Procedures of the Fund are available without charge,
upon request, by calling our toll free number (1-800-225-6292). Information
regarding how the Fund voted proxies relating to portfolio securities during the
most recent 12-month period ended June 30 is publicly available to shareowners
at us.pioneerinvestments.com. This information is also available on the
Securities and Exchange Commission's web site at http://www.sec.gov.

*   Chief Executive Officer of the Trust

**  Chief Financial and Accounting Officer of the Trust

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 37
<PAGE>

                           This page for your notes.

38 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

                           This page for your notes.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 39
<PAGE>

                           This page for your notes.

40 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

                           This page for your notes.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 41
<PAGE>

                           This page for your notes.

42 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

                           This page for your notes.

           Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12 43
<PAGE>

                           This page for your notes.

44 Pioneer Municipal High Income Trust | Semiannual Report | 10/31/12
<PAGE>

How to Contact Pioneer

We are pleased to offer a variety of convenient ways for you to contact us for
assistance or information.

You can call American Stock Transfer & Trust Company (AST) for:
--------------------------------------------------------------------------------
Account Information                                   1-800-710-0935

Or write to AST:
--------------------------------------------------------------------------------
For                                                   Write to

General inquiries, lost dividend checks,              American Stock
change of address, lost stock certificates,           Transfer & Trust
stock transfer                                        Operations Center
                                                      6201 15th Ave.
                                                      Brooklyn, NY 11219

Dividend reinvestment plan (DRIP)                     American Stock
                                                      Transfer & Trust
                                                      Wall Street Station
                                                      P.O. Box 922
                                                      New York, NY 10269-0560

Website www.amstock.com

For additional information, please contact your investment advisor or visit our
web site us.pioneerinvestments.com.

The Trust files a complete schedule of investments with the Securities and
Exchange Commission for the first and third quarters for each fiscal year on
Form N-Q. Shareowners may view the filed Form N-Q by visiting the Commission's
web site at www.sec.gov. The filed form may also be viewed and copied at the
Commission's Public Reference Room in Washington, DC. Information regarding the
operations of the Public Reference Room may be obtained by calling
1-800-SEC-0330.
<PAGE>

[LOGO] Pioneer
      Investment(R)

Pioneer Investment Management, Inc.
60 State Street
Boston, MA 02109
us.pioneerinvestments.com

Securities offered through Pioneer Funds Distributor, Inc.
60 State Street, Boston, MA 02109
Underwriter of Pioneer Mutual Funds, Member SIPC
(c) 2012 Pioneer Investments 19442-06-1212
<PAGE>

ITEM 2. CODE OF ETHICS.

(a) Disclose whether, as of the end of the period covered by the report, the
registrant has adopted a code of ethics that applies to the registrant's
principal executive officer, principal financial officer, principal accounting
officer or controller, or persons performing similar functions, regardless of
whether these individuals are employed by the registrant or a third party.  If
the registrant has not adopted such a code of ethics, explain why it has not
done so.

The registrant has adopted, as of the end of the period covered by this report,
a code of ethics that applies to the registrant's principal executive officer,
principal financial officer, principal accounting officer and controller.

(b) For purposes of this Item, the term "code of ethics" means written standards
that are reasonably designed to deter wrongdoing and to promote:

        (1) Honest and ethical conduct, including the ethical handling of actual
        or apparent conflicts of interest between personal and professional
        relationships;

        (2) Full, fair, accurate, timely, and understandable disclosure in
        reports and documents that a registrant files with, or submits to, the
        Commission and in other public communications made by the registrant;

        (3) Compliance with applicable governmental laws, rules, and
        regulations;

        (4) The prompt internal reporting of violations of the code to an
        appropriate person or persons identified in the code; and

        (5) Accountability for adherence to the code.

(c) The registrant must briefly describe the nature of any amendment, during the
period covered by the report, to a provision of its code of ethics that applies
to the registrant's principal executive officer, principal financial officer,
principal accounting officer or controller, or persons performing similar
functions, regardless of whether these individuals are employed by the
registrant or a third party, and that relates to any element of the code of
ethics definition enumerated in paragraph (b) of this Item. The registrant must
file a copy of any such amendment as an exhibit pursuant to Item 10(a), unless
the registrant has elected to satisfy paragraph (f) of this Item by posting its
code of ethics on its website pursuant to paragraph (f)(2) of this Item, or by
undertaking to provide its code of ethics to any person without charge, upon
request, pursuant to paragraph (f)(3) of this Item.

The registrant has made no amendments to the code of ethics during the period
covered by this report.

(d) If the registrant has, during the period covered by the report, granted a
waiver, including an implicit waiver, from a provision of the code of ethics to
the registrant's principal executive officer, principal financial officer,
principal accounting officer or controller, or persons performing similar
functions, regardless of whether these individuals are employed by the
registrant or a third party, that relates to one or more of the items set forth
in paragraph (b) of this Item, the registrant must briefly describe the nature
of the waiver, the name of the person to whom the waiver was granted, and the
date of the waiver.

Not applicable.

(e) If the registrant intends to satisfy the disclosure requirement under
paragraph (c) or (d) of this Item regarding an amendment to, or a waiver from,
a provision of its code of ethics that applies to the registrant's principal
executive officer, principal financial officer, principal accounting officer or
controller, or persons performing similar functions and that relates to any
element of the code of ethics definition enumerated in paragraph (b) of this
Item by posting such information on its Internet website, disclose the
registrant's Internet address and such intention.

Not applicable.

(f) The registrant must:

        (1) File with the Commission, pursuant to Item 10(a), a copy of its code
        of ethics that applies to the registrant's principal executive officer,
        principal financial officer, principal accounting officer or controller,
        or persons performing similar functions, as an exhibit to its annual
        report on this Form N-CSR (see attachment);

        (2) Post the text of such code of ethics on its Internet website and
        disclose, in its most recent report on this Form N-CSR, its Internet
        address and the fact that it has posted such code of ethics on its
        Internet website; or

        (3) Undertake in its most recent report on this Form N-CSR to provide to
        any person without charge, upon request, a copy of such code of ethics
        and explain the manner in which such request may be made.
	See Item 10(2)

ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT.

(a) (1)  Disclose that the registrant's board of trustees has determined that
         the registrant either:

    (i)  Has at least one audit committee financial expert serving on its audit
         committee; or

    (ii) Does not have an audit committee financial expert serving on its audit
         committee.

The registrant's Board of Trustees has determined that the registrant has at
least one audit committee financial expert.

    (2) If the registrant provides the disclosure required by paragraph
(a)(1)(i) of this Item, it must disclose the name of the audit committee
financial expert and whether that person is "independent." In order to be
considered "independent" for purposes of this Item, a member of an audit
committee may not, other than in his or her capacity as a member of the audit
committee, the board of trustees, or any other board committee:

    (i)  Accept directly or indirectly any consulting, advisory, or other
         compensatory fee from the issuer; or

    (ii) Be an "interested person" of the investment company as defined in
         Section 2(a)(19) of the Act (15 U.S.C. 80a-2(a)(19)).

Ms. Marguerite A. Piret, an independent trustee, is such an audit committee
financial expert.

    (3) If the registrant provides the disclosure required by paragraph (a)(1)
(ii) of this Item, it must explain why it does not have an audit committee
financial expert.

Not applicable.


ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES.

(a) Disclose, under the caption AUDIT FEES, the aggregate fees billed for each
of the last two fiscal years for professional services rendered by the principal
accountant for the audit of the registrant's annual financial statements or
services that are normally provided by the accountant in connection with
statutory and regulatory filings or engagements for those fiscal years.

N/A

(b) Disclose, under the caption AUDIT-RELATED FEES, the aggregate fees billed in
each of the last two fiscal years for assurance and related services by the
principal accountant that are reasonably related to the performance of the audit
of the registrant's financial statements and are not reported under
paragraph (a) of this Item. Registrants shall describe the nature of the
services comprising the fees disclosed under this category.

N/A

(c) Disclose, under the caption TAX FEES, the aggregate fees billed in each of
the last two fiscal years for professional services rendered by the principal
accountant for tax compliance, tax advice, and tax planning. Registrants shall
describe the nature of the services comprising the fees disclosed under this
category.

N/A

(d) Disclose, under the caption ALL OTHER FEES, the aggregate fees billed in
each of the last two fiscal years for products and services provided by the
principal accountant, other than the services reported in paragraphs (a) through
(c) of this Item. Registrants shall describe the nature of the services
comprising the fees disclosed under this category.

N/A

(e) (1) Disclose the audit committee's pre-approval policies and procedures
described in paragraph (c)(7) of Rule 2-01 of Regulation S-X.

 PIONEER FUNDS
            APPROVAL OF AUDIT, AUDIT-RELATED, TAX AND OTHER SERVICES
                       PROVIDED BY THE INDEPENDENT AUDITOR

                  SECTION I - POLICY PURPOSE AND APPLICABILITY

The Pioneer Funds recognize the importance of maintaining the independence of
their outside auditors. Maintaining independence is a shared responsibility
involving Pioneer Investment Management, Inc ("PIM"), the audit committee and
the independent auditors.

The Funds recognize that a Fund's independent auditors: 1) possess knowledge of
the Funds, 2) are able to incorporate certain services into the scope of the
audit, thereby avoiding redundant work, cost and disruption of Fund personnel
and processes, and 3) have expertise that has value to the Funds. As a result,
there are situations where it is desirable to use the Fund's independent
auditors for services in addition to the annual audit and where the potential
for conflicts of interests are minimal. Consequently, this policy, which is
intended to comply with Rule 210.2-01(C)(7), sets forth guidelines and
procedures to be followed by the Funds when retaining the independent audit firm
to perform audit, audit-related tax and other services under those
circumstances, while also maintaining independence.

Approval of a service in accordance with this policy for a Fund shall also
constitute approval for any other Fund whose pre-approval is required pursuant
to Rule 210.2-01(c)(7)(ii).

In addition to the procedures set forth in this policy, any non-audit services
that may be provided consistently with Rule 210.2-01 may be approved by the
Audit Committee itself and any pre-approval that may be waived in accordance
with Rule 210.2-01(c)(7)(i)(C) is hereby waived.

Selection of a Fund's independent auditors and their compensation shall be
determined by the Audit Committee and shall not be subject to this policy.
<PAGE>
<TABLE>
<CAPTION>
                               SECTION II - POLICY

---------------- -------------------------------- -------------------------------------------------
SERVICE           SERVICE CATEGORY DESCRIPTION      SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES
CATEGORY
---------------- -------------------------------- -------------------------------------------------
<S>              <C>                              <C>
I.  AUDIT        Services that are directly       o Accounting research assistance
SERVICES         related to performing the        o SEC consultation, registration
                 independent audit of the Funds     statements, and reporting
                                                  o Tax accrual related matters
                                                  o Implementation of new accounting
                                                    standards
                                                  o Compliance letters (e.g. rating agency
                                                    letters)
                                                  o Regulatory reviews and assistance
                                                    regarding financial matters
                                                  o Semi-annual reviews (if requested)
                                                  o Comfort letters for closed end
                                                    offerings
---------------- -------------------------------- -------------------------------------------------
II.              Services which are not           o AICPA attest and agreed-upon procedures
AUDIT-RELATED    prohibited under Rule            o Technology control assessments
SERVICES         210.2-01(C)(4) (the "Rule")      o Financial reporting control assessments
                 and are related extensions of    o Enterprise security architecture
                 the audit services support the     assessment
                 audit, or use the
                 knowledge/expertise gained
                 from the audit procedures as a
                 foundation to complete the
                 project.  In most cases, if
                 the Audit-Related Services are
                 not performed by the Audit
                 firm, the scope of the Audit
                 Services would likely
                 increase.  The Services are
                 typically well-defined and
                 governed by accounting
                 professional standards (AICPA,
                 SEC, etc.)
---------------- -------------------------------- -------------------------------------------------
<CAPTION>
 ------------------------------------- ------------------------------------
<S>                                    <C>
   AUDIT COMMITTEE APPROVAL POLICY               AUDIT COMMITTEE
                                                REPORTING POLICY
 ------------------------------------- ------------------------------------
<S>                                    <C>
 o "One-time" pre-approval             o A summary of all such
   for the audit period for all          services and related fees
   pre-approved specific service         reported at each regularly
   subcategories.  Approval of the       scheduled Audit Committee
   independent auditors as               meeting.
   auditors for a Fund shall
   constitute pre approval for
   these services.
 ------------------------------------- ------------------------------------
 o "One-time" pre-approval             o A summary of all such
   for the fund fiscal year within       services and related fees
   a specified dollar limit              (including comparison to
   for all pre-approved                  specified dollar limits)
   specific service subcategories        reported quarterly.

 o Specific approval is
   needed to exceed the
   pre-approved dollar limit for
   these services (see general
   Audit Committee approval policy
   below for details on obtaining
   specific approvals)

 o Specific approval is
   needed to use the Fund's
   auditors for Audit-Related
   Services not denoted as
   "pre-approved", or
   to add a specific service
   subcategory as "pre-approved"
 ------------------------------------- ------------------------------------
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
                     SECTION III - POLICY DETAIL, CONTINUED

----------------------- --------------------------- -----------------------------------------------
   SERVICE CATEGORY          SERVICE CATEGORY        SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES
                               DESCRIPTION
----------------------- --------------------------- -----------------------------------------------
<S>                     <C>                         <C>
III. TAX SERVICES       Services which are not      o Tax planning and support
                        prohibited by the Rule,     o Tax controversy assistance
                        if an officer of the Fund   o Tax compliance, tax returns, excise
                        determines that using the     tax returns and support
                        Fund's auditor to provide   o Tax opinions
                        these services creates
                        significant synergy in
                        the form of efficiency,
                        minimized disruption, or
                        the ability to maintain a
                        desired level of
                        confidentiality.
----------------------- --------------------------- -----------------------------------------------

------------------------------------- -------------------------
  AUDIT COMMITTEE APPROVAL POLICY         AUDIT COMMITTEE
                                          REPORTING POLICY
------------------------------------- -------------------------
------------------------------------- -------------------------
o "One-time" pre-approval             o A summary of
  for the fund fiscal  year             all such services and
  within a specified dollar limit       related fees
  				        (including comparison
  			                to specified dollar
  			                limits) reported
  			                quarterly.

o Specific approval is
  needed to exceed the
  pre-approved dollar limits for
  these services (see general
  Audit Committee approval policy
  below for details on obtaining
  specific approvals)

o Specific approval is
  needed to use the Fund's
  auditors for tax services not
  denoted as pre-approved, or to add a specific
  service subcategory as
  "pre-approved"
------------------------------------- -------------------------
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
                     SECTION III - POLICY DETAIL, CONTINUED

----------------------- --------------------------- -----------------------------------------------
   SERVICE CATEGORY          SERVICE CATEGORY        SPECIFIC PRE-APPROVED SERVICE SUBCATEGORIES
                               DESCRIPTION
----------------------- --------------------------- -----------------------------------------------
<S>                     <C>                         <C>
IV.  OTHER SERVICES     Services which are not      o Business Risk Management support
                        prohibited by the Rule,     o Other control and regulatory
A. SYNERGISTIC,         if an officer of the Fund     compliance projects
UNIQUE QUALIFICATIONS   determines that using the
                        Fund's auditor to provide
                        these services creates
                        significant synergy in
                        the form of efficiency,
                        minimized disruption,
                        the ability to maintain a
                        desired level of
                        confidentiality, or where
                        the Fund's auditors
                        posses unique or superior
                        qualifications to provide
                        these services, resulting
                        in superior value and
                        results for the Fund.
----------------------- --------------------------- -----------------------------------------------
<CAPTION>
--------------------------------------- ------------------------
    AUDIT COMMITTEE APPROVAL POLICY         AUDIT COMMITTEE
                                            REPORTING POLICY
------------------------------------- --------------------------
<S>                                   <C>
o "One-time" pre-approval             o A summary of
  for the fund fiscal year within       all such services and
  a specified dollar limit              related fees
  			               (including comparison
  			                to specified dollar
  				        limits) reported
                                        quarterly.
o Specific approval is
  needed to exceed the
  pre-approved dollar limits for
  these services (see general
  Audit Committee approval policy
  below for details on obtaining
  specific approvals)

o Specific approval is
  needed to use the Fund's
  auditors for "Synergistic" or
  "Unique Qualifications" Other
  Services not denoted as
  pre-approved to the left, or to
  add a specific service
  subcategory as "pre-approved"
------------------------------------- --------------------------
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
                     SECTION III - POLICY DETAIL, CONTINUED

----------------------- ------------------------- -----------------------------------------------
   SERVICE CATEGORY         SERVICE CATEGORY        SPECIFIC PROHIBITED SERVICE SUBCATEGORIES
                              DESCRIPTION
----------------------- ------------------------- -----------------------------------------------
<S>                     <C>                       <C>
PROHIBITED  SERVICES    Services which result     1. Bookkeeping or other services
                        in the auditors losing       related to the accounting records or
                        independence status          financial statements of the audit
                        under the Rule.              client*
                                                  2. Financial information systems design
                                                     and implementation*
                                                  3. Appraisal or valuation services,
                                                     fairness* opinions, or
                                                     contribution-in-kind reports
                                                  4. Actuarial services (i.e., setting
                                                     actuarial reserves versus actuarial
                                                     audit work)*
                                                  5. Internal audit outsourcing services*
                                                  6. Management functions or human
                                                     resources
                                                  7. Broker or dealer, investment
                                                     advisor, or investment banking services
                                                  8. Legal services and expert services
                                                     unrelated to the audit
                                                  9. Any other service that the Public
                                                     Company Accounting Oversight Board
                                                     determines, by regulation, is
                                                     impermissible
----------------------- ------------------------- -----------------------------------------------
<CAPTION>
------------------------------------------- ------------------------------
     AUDIT COMMITTEE APPROVAL POLICY               AUDIT COMMITTEE
                                                  REPORTING POLICY
------------------------------------------- ------------------------------
o These services are not to be              o A summary of all
  performed with the exception of the(*)      services and related
  services that may be permitted              fees reported at each
  if they would not be subject to audit       regularly scheduled
  procedures at the audit client (as          Audit Committee meeting
  defined in rule 2-01(f)(4)) level           will serve as continual
  the firm providing the service.             confirmation that has
  				              not provided any
                                              restricted services.
------------------------------------------- ------------------------------
</TABLE>
--------------------------------------------------------------------------------
GENERAL AUDIT COMMITTEE APPROVAL POLICY:
o For all projects, the officers of the Funds and the Fund's auditors will each
  make an assessment to determine that any proposed projects will not impair
  independence.

o Potential services will be classified into the four non-restricted service
  categories and the "Approval of Audit, Audit-Related, Tax and Other
  Services" Policy above will be applied. Any services outside the specific
  pre-approved service subcategories set forth above must be specifically
  approved by the Audit Committee.

o At least quarterly, the Audit Committee shall review a report summarizing the
  services by service category, including fees, provided by the Audit firm as
  set forth in the above policy.

--------------------------------------------------------------------------------


    (2) Disclose the percentage of services described in each of paragraphs (b)
   through (d) of this Item that were approved by the audit committee pursuant
   to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X.

N/A

(f) If greater than 50 percent, disclose the percentage of hours expended on the
principal accountant's engagement to audit the registrant's financial statements
for the most recent fiscal year that were attributed to work performed by
persons other than the principal accountant's full-time, permanent employees.

N/A

(g) Disclose the aggregate non-audit fees billed by the registrant's accountant
for services rendered to the registrant, and rendered to the registrant's
investment adviser (not including any sub-adviser whose role is primarily
portfolio management and is subcontracted with or overseen by another investment
adviser), and any entity controlling, controlled by, or under common control
with the adviser that provides ongoing services to the registrant for each of
the last two fiscal years of the registrant.

N/A

(h) Disclose whether the registrant's audit committee of the board of trustees
has considered whether the provision of non-audit services that were rendered to
the registrant's investment adviser (not including any subadviser whose role is
primarily portfolio management and is subcontracted with or overseen by another
investment adviser), and any entity controlling, controlled by, or under common
control with the investment adviser that provides ongoing services to the
registrant that were not pre-approved pursuant to paragraph (c)(7)(ii) of
Rule 2-01 of Regulation S-X is compatible with maintaining the principal
accountant's independence.

The Fund's audit committee of the Board of Trustees has
considered whether the provision of non-audit services that
were rendered to the Affiliates (as defined) that were not pre-
approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of
Regulation S-X is compatible with maintaining the principal
accountant's independence.

Item 5. Audit Committee of Listed Registrants

(a) If the registrant is a listed issuer as defined in Rule 10A-3
under the Exchange Act (17 CFR 240.10A-3), state whether
or not the registrant has a separately-designated standing
 audit committee established in accordance with Section
3(a)(58)(A) of the Exchange Act (15 U.S.C. 78c(a)(58)(A)).
If the registrant has such a committee, however designated,
identify each committee member. If the entire board of directors
is acting as the registrants audit committee as specified in
Section 3(a)(58)(B) of the Exchange Act (15 U.S.C. 78c(a)(58)(B)),
so state.

The registrant has a separately-designated standing audit
committe eestablished in accordance with Section
3(a)(58)(A) of the Exchange Act (15 U.S.C. 78c(a)(58)(A)).

(b) If applicable, provide the disclosure required by Rule 10A-3(d)
under the Exchange Act (17 CFR 240.10A-3(d)) regarding an exemption
from the listing standards for audit committees.

N/A

Item 6. Schedule of Investments.

File Schedule I Investments in securities of unaffiliated issuers
as of the close of the reporting period as set forth in 210.12-
12 of Regulation S-X [17 CFR 210.12-12], unless the schedule is
included as part of the report to shareholders filed under Item
1 of this Form.

Included in Item 1


ITEM 7. DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR
CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

A closed-end management investment company that is filing an annual report on
this Form N-CSR must, unless it invests exclusively in non-voting securities,
describe the policies and procedures that it uses to determine how to vote
proxies relating to portfolio securities, including the procedures that the
company uses when a vote presents a conflict between the interests of its
shareholders, on the one hand, and those of the company's investment adviser;
principal underwriter; or any affiliated person (as defined in Section 2(a)(3)
of the Investment Company Act of 1940 (15 U.S.C. 80a-2(a)(3)) and the rules
thereunder) of the company, its investment adviser, or its principal
underwriter, on the other. Include any policies and procedures of the company's
investment adviser, or any other third party, that the company uses, or that are
used on the company's behalf, to determine how to vote proxies relating to
portfolio securities.

Information not required in semi annual reports on form NCSR.

Item 8. Portfolio Managers of Closed-End Management Investment
        Companies.

(a) If the registrant is a closed-end management investment company that
is filing an annual report on this Form N-CSR,provide the following
information:
(1) State the name, title, and length of service of the person or persons
employed by or associated with the registrant or an investment adviser
of the registrant who are primarily responsible for the day-to-day management
of the registrants portfolio (Portfolio Manager). Also state each Portfolio
Managers business experience during the past 5 years.

Information not required in semi annual reports on form NCSR.

Item 9. Purchases of Equity Securities by Closed-End Management
Investment Company and Affiliated Purchasers.

(a) If the registrant is a closed-end management investment company,
in the following tabular format, provide the information specified in
paragraph (b) of this Item with respect to any purchase made by or on
behalf of the registrant or any affiliated purchaser, as defined in
Rule 10b-18(a)(3) under the Exchange Act (17 CFR 240.10b-18(a)(3)), of
shares or other units of any class of the registrants equity securities
that is registered by the registrant pursuant to Section 12 of the
Exchange Act (15 U.S.C. 781). Instruction to paragraph (a). Disclose
all purchases covered by this Item, including purchases that do not
satisfy the conditions of the safe harbor of Rule 10b-18 under the
Exchange Act (17 CFR 240.10b-18), made in the period covered by the
report. Provide disclosures covering repurchases made on a monthly basis.
For example, if the reporting period began on January 16 and ended on
July 15, the chart would show repurchases for the months from January 16
through February 15, February 16 through March 15, March 16 through
April 15, April 16 through May 15, May 16 through June 15, and June 16
through July 15.

During the period covered by this report, there were no purchases
made by or on behalf of the registrant or any affiliated purchaser
as defined in Rule 10b-18(a)(3) under the Securities Exchange Act
of 1934 (the Exchange Act), of shares of the registrants equity
securities that are registered by the registrant pursuant to
Section 12 of the Exchange Act.


Item 10. Submission of Matters to a Vote of Security Holders.

Describe any material changes to the procedures by which shareholders
may recommend nominees to the registrants board of directors, where
those changes were implemented after the registrant last provided
disclosure in response to the requirements of Item 7(d)(2)(ii)(G)
of Schedule 14A (17 CFR 240.14a-101), or this Item.


There have been no material changes to the procedures by which the
shareholders may recommend nominees to the registrants board of
directors since the registrant last provided disclosure in response
to the requirements of Item 7(d)(2)(ii)(G) of Schedule 14(A) in
its definitive proxy statement, or this Item.


ITEM 11. 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-2(c) under the Act (17 CFR
270.30a-2(c))) based on their evaluation of these controls and procedures as of
a date within 90 days of the filing date of the report that includes the
disclosure required by this paragraph.

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 whether or not there were significant changes in the registrant's
internal controls or in other factors that could significantly affect these
controls subsequent to the date of their evaluation, including any corrective
actions with regard to significant deficiencies and material weaknesses.

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.

The registrant's principal executive officer and principal financial
officer, however, voluntarily are reporting the following information:

In August of 2006 the registrant's investment adviser
enhanced its internal procedures for reporting performance
information required to be included in prospectuses.
Those enhancements involved additional internal controls
over the appropriateness of performance data
generated for this purpose.  Such enhancements were made
following an internal review which identified
prospectuses relating to certain classes of shares of
a limited number of registrants where, inadvertently,
performance information not reflecting the deduction of
applicable sales charges was included. Those prospectuses
were revised, and the revised prospectuses were distributed to
shareholders.


ITEM 12. EXHIBITS.

File the exhibits listed below as part of this Form. Letter or number the
exhibits in the sequence indicated.

(a) Any code of ethics, or amendment thereto, that is the subject of the
disclosure required by Item 2, to the extent that the registrant intends to
satisfy the Item 2 requirements through filing of an exhibit.



(b) 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 December 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 December 28, 2012


By (Signature and Title)* /s/ Mark Bradley
Mark Bradley, Treasurer & Chief Accounting & Financial Officer

Date December 28, 2012

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