SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* ZAX STANLEY R (Last) (First) (Middle) 21255 CALIFA ST. (Street) WOODLAND HILLS CA 91367 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol ZENITH NATIONAL INSURANCE CORP [ ZNT ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner X Officer (give title below) Other (specify below) President & Chairman
	3. Date of Earliest Transaction (Month/Day/Year) 03/18/2004
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock								337	I	By Son(3)
Common Stock								337	I	By Daughter(3)
Common Stock								356	I	By Daughter(3)
Common Stock	03/18/2004		F(1)		121,015	D	$39.24	126,519	D
Common Stock	03/18/2004		M		201,000	A	$23.625	327,519	D
Common Stock	03/19/2004		S(2)		400	D	$39.33	327,119	D
Common Stock	03/19/2004		S(2)		100	D	$39.31	327,019(5)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Employee Stock Option (right to buy)	$23.625	03/18/2004		M			201,000	(4)	03/14/2006	Common Stock	201,000	$0	799,000	D

Explanation of Responses:

1. 121,015 shares of common stock previously held by the reporting person were tendered to the issuer in payment of the aggregate exercise price of $4,748,625 for the Employee Stock Option based on the closing price of $39.24 per share for the common stock on the New York Stock Exchange on March 18, 2004.

2. In connection with his above described exercise of options, Mr. Zax instructed Zenith to sell on his behalf a number of the newly acquired shares of Zenith Common Stock sufficient to reimburse Zenith for withholding taxes Zenith is obligated to remit to taxing authorities related to such option exercise, and the reported sales of shares of Zenith Common Stock were made pursuant to such instructions. The sale of these shares are covered in the Form 144 Notice of Proposed Sale of 30,000 shares filed by Mr. Zax on March 19, 2004.

3. These securities are held by the reporting person as custodian for the reporting person's adult children. The reporting person disclaims beneficial ownership of these securities, and this report shall not be deemed an admission that the reproting person is the beneficial owner of such securities for pruposes of Section 16 or any other purpose.

4. Employee stock option exercisable for a total of 1,000,000 shares became exercisable as to 200,000 shares on each March 15, 1997, 1998, 1999, 2000 and 2001.

5. A summary of this filing follows: Mr. Zax's direct holdings of Zenith Common Stock prior to his surrender of shares in payment of the aggregate exercise price for his employee stock option exercise on 3/18/04 was 247,534. 121,015 shares were surrendered on 3/18/04 and Mr. Zax received 201,000 shares of Zenith Common Stock from his exercise of options on 3/18/04.The total number of Zenith shares sold for withholding taxes through 3/19/04 is 500 and Mr. Zax's direct holding of Zenith Common Stock as of 3/19/04 is 327,019.The Zenith shares remaining to be sold under Mr. Zax's Form 144 filed on 3/19/04 is 29,500 as of 3/19/04.

	/s/ Stanley R. Zax	03/22/2004
	** Signature of Reporting Person	Date
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