Zenith National Insurance (ZNT) 10-Q 2007 Q1 Quarterly report

Exhibit 32

CERTIFICATION OF CHIEF EXECUTIVE OFFICER AND CHIEF FINANCIAL OFFICER
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 on Form 10-Q of Zenith National Insurance Corp. (the “Company”) for the quarterly period ended March 31, 2007, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), Stanley R. Zax, as Chief Executive Officer of the Company, and Kari L. Van Gundy, as Chief Financial Officer of the Company, each hereby certifies, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that, to the best of his and her knowledge:

(1)The Report fully complies with the requirements of Section 13(a) or 15(d) 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.

Date:April 23, 2007

/s/ Stanley R. Zax

Stanley R. Zax

Chairman of the Board and President

(Chief Executive Officer)

/s/ Kari L. Van Gundy

Kari L. Van Gundy

Senior Vice President and Chief Financial Officer

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