INDEPENDENT AUDITORS' REPORT
To the Trustees and Shareholders of MFS Series Trust IX:
In planning and performing our audits of the financial statements of MFS Bond
Fund, MFS Limited Maturity Fund, MFS Municipal Limited Maturity Fund, MFS
Research Bond Fund, and MFS Intermediate Investment Grade Bond Fund (series of
MFS Series Trust IX) (the "Trust") for the year ended April 30, 2000 (on which
we have issued our reports dated June 7, 2000), we considered its internal
control, including control activities for safeguarding securities, in order to
determine our auditing procedures for the purpose of expressing our opinions on
the financial statements and to comply with the requirements of Form N-SAR, and
not to provide assurance on the Trust's internal control.
The management of the Trust is responsible for establishing and maintaining
internal control. In fulfilling this responsibility, estimates and judgments by
management are required to assess the expected benefits and related costs of
controls. Generally, controls that are relevant to an audit pertain to the
entity's objective of preparing financial statements for external purposes that
are fairly presented in conformity with generally accepted accounting
principles. Those controls include the safeguarding of assets against
unauthorized acquisition, use or disposition.
Because of inherent limitations in any internal control, misstatements due to
error or fraud may occur and not be detected. Also, projections of any
evaluation of internal control to future periods is subject to the risk that the
internal control may become inadequate because of changes in conditions or that
the degree of compliance with policies or procedures deteriorates.
Our consideration of the Trust's internal control would not necessarily disclose
all matters in internal control 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 one or
more of the internal control components does not reduce to a relatively low
level the risk that misstatements caused by error or fraud 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
Trust's internal control and its operation, including controls for safeguarding
securities that we consider to be material weaknesses as defined above as of
April 30, 2000.
This report is intended solely for the information and use of management, the
Trustees and Shareholders of MFS Series Trust IX, 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
June 7, 2000
