Report of Independent Registered Public Accounting Firm

To the Shareholders and
Board of Trustees of UBS Series Funds

In planning and performing our audits of the financial statements
of UBS Series Funds (comprising, respectively, UBS Liquid
Assets Government Fund, Limited Purpose Cash Investment
Fund, UBS Ultra Short Income Fund, UBS RMA Government
Money Market Fund, UBS Select Prime Preferred Fund, UBS
Select Government Preferred Fund, UBS Select Treasury
Preferred Fund, UBS Prime Preferred Fund, UBS Tax-Free
Preferred Fund, UBS Select Prime Institutional Fund, UBS Select
Government Institutional Fund, UBS Select Treasury Institutional
Fund, UBS Prime Reserves Fund, UBS Tax-Free Reserves Fund,
UBS Select Prime Investor Fund, UBS Select Government
Investor Fund, UBS Select Treasury Investor Fund, UBS Prime
Investor Fund, UBS Tax-Free Investor Fund, UBS Select
Government Capital Fund and UBS Select Treasury Capital
Fund) (the "Company") as of and for the period ended April 30,
2019, 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-CEN, 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 U.S. 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 U.S. generally accepted accounting principles,
and that receipts and expenditures of the company are being made
only in accordance with authorizations of management and
trustees 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 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 April 30, 2019.

This report is intended solely for the information and use of
management and the Board of Trustees of UBS Series Funds, and
the Securities and Exchange Commission and is not intended to
be and should not be used by anyone other than these specified
parties.

/s/ ERNST & YOUNG LLP

New York, New York
July 2, 2019