FOURTH AMENDMENT TO
                              CREDIT AGREEMENT



     THIS FOURTH AMENDMENT TO CREDIT AGREEMENT (this "Amendment") dated as of
July 22, 1999 is entered into between ZENITH NATIONAL INSURANCE CORP. (the
"Company"), and BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIATION (the
"Bank").

                              W I T N E S S E T H:

     WHEREAS, the Company and the Bank are parties to that certain Credit
Agreement dated as of July 24, 1997 (as amended, herein called the "Credit
Agreement"; terms used but not otherwise defined herein are used herein as
defined in the Credit Agreement); and

     WHEREAS, the Company and the Bank desire to make certain amendments to
the Credit Agreement on the terms and conditions set forth herein;

     NOW, THEREFORE, in consideration of the premises, and intending to be
legally bound hereby, the Company and the Bank hereby agree as follows:

     SECTION 1.  AMENDMENTS.

     Subject to and upon the terms and conditions hereof and in reliance on
the Company's warranties set forth in SECTION 2 below, as of the date hereof
the Credit Agreement is amended by amending clause (a) of the definition of
"Tranche A Termination Date" set forth in Section 1.1 of the Credit Agreement
to delete the reference to July 22, 1999 contained therein and replacing it
with August 20, 1999.

     SECTION 2.  WARRANTIES.

     To induce the Bank to enter into this Amendment, the Company warrants to
the Bank as of the date hereof that:

     (a) After giving effect to this Amendment, all representations and
warranties contained in the Credit Agreement and the Loan Documents are true
and correct in all material respects on and as of the date hereof (except to
the extent such representations and warranties expressly refer to an earlier
date).

     (b) After giving effect to this Amendment, no Default or Event of
Default has occurred and is continuing.

     (c) The execution, delivery and performance by the Company of this
Amendment have been duly authorized by all necessary corporate and other
action and do not and will not require any registration with, consent or
approval of, notice to or action by, any



Person (including any governmental authority) in order to be effective and
enforceable.  The Credit Agreement as modified by this Amendment constitutes
the legal, valid and binding obligation of the Company, enforceable against
it in accordance with the Credit Agreement's terms, without defense,
counterclaim or offset.

     SECTION 3.  GENERAL.

     (a) As hereby modified, the Credit Agreement shall remain in full force
and effect and is hereby ratified, approved and confirmed in all respects.

     (b) The Company acknowledges and agrees that the execution and delivery
by the Bank of this Amendment shall not be deemed to create a course of
dealing or otherwise obligate the Bank to execute similar modifications under
the same or similar circumstances in the future.

     (c) This Amendment may be executed in any number of counterparts and by
the different parties on separate counterparts, and each such counterpart
shall be deemed to be an original, but all such counterparts shall together
constitute but one and the same Amendment.

Delivered at Chicago, Illinois, as of the date and year first above written.


                                      BANK OF AMERICA NATIONAL TRUST AND
                                      SAVINGS ASSOCIATION


                                      By: /s/ Jim V. Miller
                                         -------------------------------------
                                      Name:  Jim V. Miller
                                           -----------------------------------
                                      Title:  Managing Director
                                            ----------------------------------


                                      ZENITH NATIONAL INSURANCE CORP.


                                      By: /s/ Stanley R. Zax
                                         -------------------------------------
                                      Name:  Stanley R. Zax
                                           -----------------------------------
                                      Title: Chairman & President
                                            ----------------------------------

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