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SIGNATURE ROBERT P. NAULT
TITLE ASST. SECRETARY
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REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
To the Board of Trustees of
Pioneer Mid-Cap Fund:
In planning and performing our audit of the financial statements of Pioneer
Mid-Cap Fund for the year ended September 30, 1997, we considered its internal
control structure, including procedures for safeguarding securities, in order to
determine our auditing procedures for the purpose of expressing our opinion on
the financial statements and to comply with the requirements of Form N-SAR, not
to provide assurance on the internal control structure.
The management of Pioneer Mid-Cap Fund is responsible for establishing and
maintaining an internal control structure. In fulfilling this responsibility,
estimates and judgements by management are required to assess the expected
benefits and related costs of internal control structure policies and
procedures. Two of the objectives of an internal control structure are to
provide management with reasonable, but not absolute, assurance that assets are
safeguarded against loss from unauthorized use or disposition and transactions
are executed in accordance with management's authorization and recorded properly
to permit preparation of financial statements in conformity with generally
accepted accounting principles.
Because of inherent limitations in any internal control structure, errors or
irregularities may occur and may not be detected. Also projection of any
evaluation of the structure to future periods is subject to the risk that it may
become inadequate because of changes in conditions or that the effectiveness of
the design and operation may deteriorate.
Our consideration of the internal control structure would not necessarily
disclose all matters in the internal control structure that might be material
weaknesses under standards established by the American Institute of Certified
Public Accountants. A material weakness is a condition in which the design or
operation of the specific internal control structure elements does not reduce to
a relatively low level the risk that errors or irregularities in amounts that
would be material in relation to the financial statements being audited may
occur and not be detected within a timely period by employees in the normal
course of performing their assigned functions. However, we noted no matters
involving the internal control structure, including procedures for safeguarding
securities, that we consider to be material weaknesses as defined above as of
September 30, 1997.
This report is intended solely for the information and use of management and the
Securities and Exchange Commission.
/s/ Arthur Andersen LLP
Boston, Massachusetts
October 31, 1997
