REPORT OF INDEPENDENT REGISTERED
PUBLIC ACCOUNTING FIRM

To the Board of Trustees and Shareowners of
Pioneer Mid Cap Value Fund:
In planning and performing our audit of the
financial statements of Pioneer Mid Cap Value
Fund (the "Fund") as of and for the year ended
October 31, 2016, 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 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 fund'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 generally accepted
accounting principles.  A fund'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 fund; (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 fund are being
made only in accordance with authorizations of
management and trustees of the fund; and (3)
provide reasonable assurance regarding prevention
or timely detection of unauthorized acquisition, use,
or disposition of a fund'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 a fund'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 for safeguarding
securities that we consider to be a material
weakness, as defined above, as of October 31, 2016.
This report is intended solely for the information
and use of management and the Board of Trustees
of Pioneer Mid Cap Value Fund and the Securities
and Exchange Commission and is not intended to be
and should not be used by anyone other than these
specified parties.

Deloitte & Touche LLP
Boston, Massachusetts
December 23, 2016