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                                                              Exhibit EX-99.CERT

                                 CERTIFICATIONS

I, Joseph A. Varnas, President of UBS Municipal Money Market Series certify
that:

1.     I have reviewed this report on Form N-CSR of UBS Municipal Money Market
       Series;

2.     Based on my knowledge, this report does not contain any untrue statement
       of a material fact or omit to state a material fact necessary to make the
       statements made, in light of the circumstances under which such
       statements were made, not misleading with respect to the period covered
       by this report;

3.     Based on my knowledge, the financial statements, and other financial
       information included in this report, fairly present in all material
       respects the financial condition, results of operations, changes in net
       assets, and cash flows (if the financial statements are required to
       include a statement of cash flows) of the registrant as of, and for, the
       periods presented in this report;

4.     The registrant's other certifying officer(s) and I are responsible for
       establishing and maintaining disclosure controls and procedures (as
       defined in Rule 30a-3(c) under the Investment Company Act of 1940) for
       the registrant and have:

            (a) Designed such disclosure controls and procedures, or caused
                such disclosure controls and procedures to be designed under our
                supervision, to ensure that material information relating to the
                registrant, including its consolidated subsidiaries, is made
                known to us by others within those entities, particularly during
                the period in which this report is being prepared;

            (b) Evaluated the effectiveness of the registrant's disclosure
                controls and procedures and presented in this report our
                conclusions about the effectiveness of the disclosure controls
                and procedures, as of a date within 90 days prior to the filing
                date of this report based on such evaluation; and

            (c) Disclosed in this report any change in the registrant's
                internal control over financial reporting that occurred during
                the registrant's most recent fiscal half-year (the registrant's
                second fiscal half-year in the case of an annual report) that
                has materially affected, or is reasonably likely to materially
                affect, the registrant's internal control over financial
                reporting; and

5.     The registrant's other certifying officer(s) and I have disclosed to the
       registrant's auditors and the audit committee of the registrant's board
       of directors (or persons performing the equivalent functions):

            (a) All significant deficiencies and material weaknesses in the
                design or operation of internal control over financial reporting
                which are reasonably likely to adversely affect the registrant's
                ability to record, process, summarize, and report financial
                information; and

            (b) Any fraud, whether or not material, that involves management or
                other employees who have a significant role in the registrant's
                internal control over financial reporting.

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By:    /s/ Joseph A. Varnas
       --------------------
       Joseph A. Varnas
       President

Date:  March 5, 2004
       -------------

I, Paul H. Schubert, Treasurer of UBS Municipal Money Market Series, certify
that:

1.     I have reviewed this report on Form N-CSR of UBS Municipal Money Market
       Series;

2.     Based on my knowledge, this report does not contain any untrue statement
       of a material fact or omit to state a material fact necessary to make the
       statements made, in light of the circumstances under which such
       statements were made, not misleading with respect to the period covered
       by this report;

3.     Based on my knowledge, the financial statements, and other financial
       information included in this report, fairly present in all material
       respects the financial condition, results of operations, changes in net
       assets, and cash flows (if the financial statements are required to
       include a statement of cash flows) of the registrant as of, and for, the
       periods presented in this report;

4.     The registrant's other certifying officer(s) and I are responsible for
       establishing and maintaining disclosure controls and procedures (as
       defined in Rule 30a-3(c) under the Investment Company Act of 1940) for
       the registrant and have:

            (a) Designed such disclosure controls and procedures, or caused
                such disclosure controls and procedures to be designed under our
                supervision, to ensure that material information relating to the
                registrant, including its consolidated subsidiaries, is made
                known to us by others within those entities, particularly during
                the period in which this report is being prepared;

            (b) Evaluated the effectiveness of the registrant's disclosure
                controls and procedures and presented in this report our
                conclusions about the effectiveness of the disclosure controls
                and procedures, as of a date within 90 days prior to the filing
                date of this report based on such evaluation; and

            (c) Disclosed in this report any change in the registrant's
                internal control over financial reporting that occurred during
                the registrant's most recent fiscal half-year (the registrant's
                second fiscal half-year in the case of an annual report) that
                has materially affected, or is reasonably likely to materially
                affect, the registrant's internal control over financial
                reporting; and

5.     The registrant's other certifying officer(s) and I have disclosed to the
       registrant's auditors and the audit committee of the registrant's board
       of directors (or persons performing the equivalent functions):

            (a) All significant deficiencies and material weaknesses in the
                design or operation of internal control over financial reporting
                which are reasonably likely to adversely affect the registrant's
                ability to record, process, summarize, and report financial
                information; and

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            (b) Any fraud, whether or not material, that involves management or
                other employees who have a significant role in the registrant's
                internal control over financial reporting.

By:    /s/ Paul H. Schubert
       --------------------
       Paul H. Schubert
       Treasurer

Date:  March 5, 2004
       -------------