SECURITIES AND EXCHANGE COMMISSION

                              WASHINGTON, DC 20549



                                   -----------



                                    FORM 8-A

                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                    PURSUANT TO SECTION 12(B) OR 12(G) OF THE
                         SECURITIES EXCHANGE ACT OF 1934



                       PIONEER MUNICIPAL HIGH INCOME TRUST
             (Exact Name of Registrant as Specified in Its Charter)


                               DELAWARE                     030512430
             --------------------------------------------   ----------
             (State of Incorporation or Organization)       (I.R.S. Employer
                                                            Identification
                                                            Number)

                    60 STATE STREET, BOSTON, MA               02109
             --------------------------------------------   ----------
             (Address of Principal Executive Offices)       (Zip Code)



                                                         
        If this form relates to the                         If this form relates to the
        registration of a class of securities               registration of a class of securities
        pursuant to Section 12(b) of the                    pursuant to Section 12(g) of the
        Exchange Act and is effective                       Exchange Act and is effective
        pursuant to General Instruction                     pursuant to General Instruction
        A. (c), please check the following                  A (d), please check the following
        box.  [X]                                           box.  [   ]

        Securities Act registration statement file number to which this form relates:  FILE NO. 333-103836
                                                                                       ------------------

        Securities to be registered pursuant to Section 12(b) of the Act:


                  Title of Each Class                                  Name of Each Exchange on Which
                  TO BE SO REGISTERED                                  EACH CLASS IS TO BE REGISTERED
                  -------------------                                  ------------------------------
                  Common Shares of Beneficial Interest,                New York Stock Exchange, Inc.
                  No Par Value


        Securities to be registered pursuant to Section 12(g) of the Act: None.

                             Total Number of Pages 3

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BOSTON 1691329v2


                 INFORMATION REQUIRED IN REGISTRATION STATEMENT


Item 1.        Description of Registrant's Securities to be Registered.

     The  description  of the  Registrant's  common  shares to be  registered is
incorporated by reference to the description  under the heading  "Description of
Shares" in the  Registrant's  Preliminary  Prospectus  dated July 1, 2003, which
forms part of  Pre-Effective  Amendment No. 2 to the  Registrant's  Registration
Statement on Form N-2 (File No. 333-103836;  811-21321) as electronically  filed
pursuant to Rule 497 under the Securities Exchange Act of 1933, as amended, with
the  Securities  and  Exchange   Commission  on  July  2,  2003  (Accession  No.
0001016964-03-000160), which is incorporated herein by reference.

Item 2.        Exhibits.

Pursuant to the  instructions as to Exhibits,  no exhibits are filed herewith or
incorporated by reference.


                                                              page 2 of 3
BOSTON 1691329v2




                                    SIGNATURE


     Pursuant to the  requirements of Section 12 of the Securities  Exchange Act
of 1934, the registrant has duly caused this registration statement to be signed
on its behalf by the undersigned, thereto duly authorized.





Date:  July 2, 2003                Pioneer Municipal High Income Trust
                                -----------------------------------------------
                                   (Registrant)


                           By:      /s/ Dorothy E. Bourassa
                                -----------------------------------------------
                                    (Signature)

                                     Dorothy E. Bourassa
                                -----------------------------------------------
                                     (Name)
                           Its:     Assistant Secretary
                                -----------------------------------------------



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BOSTON 1691329v2