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<PAGE> PAGE 3
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SIGNATURE ALEX M. CICCONE
TITLE ASSISTANT SECRETARY
<TABLE> <S> <C>
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<CIK> 0000102401
<NAME> USAA MUTUAL FUND, INC.
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<NAME> USAA S&P 500 INDEX FUND
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</TABLE>
To the Shareholders of USAA S&P 500 Index Fund
and Board of Directors USAA Mutual Fund, Inc.:
In planning and performing our audit of the financial statements and financial
highlights of USAA S&P 500 Index Fund (the "Fund") for the year ended December
31, 1998, we considered its internal control, including controls activities for
safeguarding securities, in order to determine our auditing procedures for the
purpose of expressing our opinion on the financial statements and financial
highlights and to comply with the requirements of Form N-SAR, not to provide
assurance on internal control.
The management of the Fund 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 and financial highlights
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 internal control, error or fraud may occur
and not be detected. Also, projection of any evaluation of internal control 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 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 and financial highlights 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 and its operation, including controls
over safeguarding securities, that we consider to be material weaknesses as
defined above as of December 31, 1998.
This report is intended solely for the information and use of management, the
Board of Directors of the USAA Mutual Fund, Inc., and the Securities and
Exchange Commission.
PricewaterhouseCoopers LLP
Baltimore, Maryland
February 1, 1999