<DOCUMENT>
<TYPE>EX-99.77B ACCT LTTR
<SEQUENCE>3
<FILENAME>b77.txt
<TEXT>


             Report of Independent Registered Public Accounting Firm

To the Shareholders and Board of Trustees of
MFS High Yield Municipal Trust

In planning and  performing  our audit of the financial statements of MFS High
Yield   Municipal   Trust   (the   Fund)   as of  and  for  the   year ended
dateYear2008Day30Month11lstransNovember   30,  2008,  in  accordance  with the
standards of the Public Company Accounting Oversight Board (United States), we
considered  the Fund's  internal  control over  financial reporting, including
controls  over safeguarding  securities, as a basis for designing our auditing
procedures for the purpose of expressing our opinion on the financial statements
and to comply with the requirements  of Form N-SAR, but not for the purpose of
expressing an opinion on the effectiveness  of the Funds internal control over
financial reporting. Accordingly, we express no such opinion.

The  management of the Fund is responsible  for establishing  and  maintaining
effective  internal  control  over  financial  reporting.  In fulfilling  this
responsibility, estimates and judgments by management are required to assess the
expected  benefits and related costs of controls. A companys internal control
over financial reporting is a process designed to provide reasonable assurance
regarding  the reliability  of  financial  reporting  and  the preparation of
financial statements for external purposes in accordance with generally accepted
accounting  principles. A company's  internal control over financial  reporting
includes those policies and  procedures  that (1) pertain to the maintenance of
records  that,  in  reasonable  detail,  accurately  and  fairly  reflect  the
transactions  and  dispositions of the assets of  the  company  (2) provide
reasonable  assurance  that  transactions  are  recorded as  necessary to permit
preparation  of financial statements  in  accordance  with  generally accepted
accounting  principles, and that receipts and  expenditures  of the company are
being made only in accordance with authorizations of management and directors of
the company and (3) provide reasonable assurance regarding prevention or timely
detection of unauthorized acquisition, use or disposition of a companys assets
that could have a material effect on the financial statements.

Because of its inherent  limitations, internal control over financial reporting
may not prevent or detect misstatements. Also, projections of any evaluation of
effectiveness to future periods are subject to the risk that controls may become
inadequate  because of changes in  conditions, or that the degree of compliance
with the policies or procedures may deteriorate.

A deficiency in internal control over financial reporting exists when the design
or operation of a control does not allow management or employees, in the normal
course  of  performing   their  assigned   functions, to  prevent  or  detect
misstatements  on a timely  basis. A material  weakness is a  deficiency, or a
combination of deficiencies, in internal control over financial reporting, such
that  there is a  reasonable possibility  that a material  misstatement  of the
company's  annual or  interim financial statements  will not be  prevented or
detected on a timely basis.

Our consideration of the Fund's internal control over financial  reporting was
for the limited purpose described  in the  first  paragraph  and  would  not
necessarily disclose all deficiencies in internal control that might be material
weaknesses  under standards established  by the  Public  Company  Accounting
Oversight  Board  (United States).  However,  we  noted  no
deficiencies  in the Funds internal  control over financial reporting and its
operation, including controls over safeguarding securities, that we consider to
be   a   material   weakness  as  defined   above  as of
November 30, 2008.

This report is intended solely for the information and use of management and the
Board of Trustees of MFS High Yield  Municipal  Trust and the  Securities  and
Exchange Commission and is not intended to be and should not be used by anyone
other than these specified parties.


Boston, Massachusetts

January 20, 2009



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