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 November 30, 2020, 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-CEN, but not for the purpose of
expressing an opinion on the effectiveness of the Fund's
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 company's
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 U.S.
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 U.S. 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 company's 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 Fund's 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, 2020.
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.


/s/ Ernst & Young LLP

Boston, Massachusetts
January 14, 2021