EXHIBIT 32.2

                   CERTIFICATION PURSUANT TO 18 U.S.C. SECTION
                 1350 AS ADOPTED PURSUANT TO SECTION 906 OF THE
                           SARBANES-OXLEY ACT OF 2002

         In connection with the Quarterly Report of Castelle (the "Company") on
Form 10-Q for the period ended March 31, 2005, as filed with the Securities and
Exchange Commission on the date hereof (the "Report"), I, Paul Cheng, Chief
Financial Officer of the Company, certify, pursuant to 18 U.S.C. ss. 1350, as
adopted pursuant to ss. 906 of the Sarbanes-Oxley Act of 2002, that to my
knowledge:

(1)      The Report fully complies with the  requirements of Section 13(a) of
         the Securities  Exchange Act of 1934; and

(2)      The information contained in the Report fairly presents, in all
         material respects, the financial condition and results of operations of
         the Company.



          /s/ Paul Cheng
Name:    Paul Cheng
Title:   Chief Financial Officer

Date:    May 13, 2005


This certification accompanies this report pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002 and shall not be deemed to be filed by Castelle for
purposes of Section 18 of the Securities Exchange Act of 1934. A signed original
of this written statement required by Section 906 has been provided to Castelle
and will be retained by Castelle and furnished to the Securities and Exchange
Commission or its staff upon request.



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