N-CSR Item 10 - Exhibits: Certifications EX-99.906CERT

                            SECTION 906 CERTIFICATION

Pursuant to 18 U.S.C.ss.  1350, the undersigned officers of Cash Trust Series on
behalf of Government Cash Series,  Municipal Cash Series, Prime Cash Series, and
Treasury  Cash Series (the  "Registrant"),  hereby  certify,  to the best of our
knowledge,  that the  Registrant's  Report on Form  N-CSR for the  period  ended
5/31/03 (the "Report") fully complies with the  requirements of Section 13(a) or
15(d),  as  applicable,  of the Securities and Exchange Act of 1934 and that the
information  contained in the Report fairly presents,  in all material respects,
the financial condition and results of operations of the Registrant.


Dated: July 28, 2003

/s/ J. Christopher Donahue

Title: President, Principal Executive Officer



Dated: July 28, 2003

/s/ Richard J. Thomas

Title: Treasurer, Principal Financial Officer

This certification is being furnished solely pursuant to 18 U.S.C.ss. 1350 and
is not being filed as part of the Report or as a separate disclosure document.