Exhibit 23

            Consent of Independent Registered Public Accounting Firm

The Board of Directors
Cass Information Systems, Inc.:

We consent to the incorporation by reference in the registration statement (Nos.
333-44499, 333-91456, and 333-91568) on Form S-8 of Cass Information Systems,
Inc. of our reports dated March 11, 2005, with respect to the consolidated
balance sheets of Cass Information Systems, Inc. as of December 31, 2004 and
2003, and the related consolidated statements of income, cash flows, and
shareholders' equity and comprehensive income for each of the years in the
three-year period ended December 31, 2004, management's assessment of the
effectiveness of internal control over financial reporting as of December 31,
2004 and the effectiveness of internal control over financial reporting as of
December 31, 2004, which reports appear in the December 31, 2004 annual report
on Form 10-K of Cass Information Systems, Inc.


/s/ KPMG LLP

St. Louis, Missouri
March 15, 2005