REPORT OF INDEPENDENT REGISTERED PUBLIC
ACCOUNTING FIRM

To the Shareholders and Board of Trustees of
Morgan Stanley Developing Growth Securities Trust:

In planning and performing our audit of the financial statements of
Morgan Stanley Developing Growth Securities Trust (the Fund) as of
and for the year ended September 30, 2005, in accordance with the
standards of the Public Company Accounting Oversight Board (United
States), we considered its internal control over financial reporting,
including control activities for 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.
Such internal control includes policies and procedures that 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 control deficiency 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 significant deficiency is a control deficiency, or
combination of control deficiencies, that adversely affects the fund’s
ability to initiate, authorize, record, process or report financial data
reliably in accordance with generally accepted accounting principles
such that there is more than a remote likelihood that a misstatement of
the fund’s annual or interim financial statements that is more than
inconsequential will not be prevented or detected. A material weakness
is a significant deficiency, or combination of significant deficiencies,
that results in more than a remote likelihood that a material misstatement
of the annual or interim financial statements will not be prevented or
detected.

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
significant deficiencies or 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 September 30, 2005.

This report is intended solely for the information and use of management
and the Board of Trustees of Morgan Stanley Developing Growth
Securities 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.



New York, New York
November 21, 2005