Report of Independent Registered Public Accounting
Firm

To the Shareowners and
Board of Trustees of Pioneer Series Trust I
In planning and performing our audit of the financial
statements of Pioneer Series Trust I  (the Company) as of
and for the year ended November 30, 2010 in accordance
with the standards of the Public Company Accounting
Oversight Board (United States), we considered the
Company'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 Company's internal control over financial reporting.
Accordingly, we express no such opinion.
The management of the Company 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 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 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 Company'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 Company'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, 2010.
This report is intended solely for the information and use of
management and the Board of Trustees of Pioneer Series
Trust I and the Securities and Exchange Commission and
is not intended to be and should not be used by anyone
other than these specified parties.


Ernst & Young LLP


Boston, Massachusetts
January 26, 2011