Cash Trust Series, Inc.

Federated Investors Funds

5800 Corporate Drive

Pittsburgh, Pennsylvania 15237-7000

August 1, 2008

EDGAR Operations Branch

U.S. Securities and Exchange Commission

Division of Investment Management

100 F Street, N.E.

Washington, DC  20549

RE:              Cash Trust Series, Inc. the “Trust”

Government Cash Series

Municipal Cash Series

Prime Cash Series

Treasury Cash Series

1933 Act File No. 33-29838

1940 Act File No. 811-5843

Dear Sir or Madam:

Pursuant to Rule 497(j) of the Securities Act of 1933, the above-referenced Trust hereby certifies that the definitive forms of Prospectuses and Statements of Additional Information dated July 31, 2008, that would have been filed under Rule 497(c), does not differ from the forms of Prospectuses and Statements of Additional Information contained in the most recent Registration Statement for the Trust.  This Registration Statement was electronically filed under Rule 485(b) as Post-Effective amendment No. 29 on July 29, 2008.

If you have any questions regarding this certification, please contact me at (412) 288-7268.

Very truly yours,

/s/ George Magera

George Magera

Assistant Secretary