Zenith Files 4.0% Increase In Its California Workers` Compensation Rates Effective July 1, 2009

WOODLAND HILLS, Calif.--(Business Wire)--
Zenith National Insurance Corp. (NYSE:ZNT) announced that its wholly owned
subsidiary, Zenith Insurance Company, filed new workers` compensation rates
today with the California Department of Insurance. The new rates will go into
effect in California starting July 1, 2009 and represent an average increase of
4.0% when compared to rates in effect since January 1, 2009. Rates charged to
employers are also affected by changes in experience modification factors and
net credits and debits applied to individual accounts.

The Private Securities Litigation Reform Act of 1995 provides a safe harbor for
forward-looking statements if accompanied by meaningful cautionary statements
identifying important factors that could cause actual results to differ
materially from those discussed. Forward-looking statements include those
related to the plans and objectives of management for future operations, future
economic performance, or projections of revenues, income, earnings per share,
capital expenditures, dividends, capital structure, or other financial items.
Statements containing words such as expect, anticipate, believe, estimate,
likely or similar words that are used in this release or in other written or
oral information conveyed by or on behalf of Zenith are intended to identify
forward-looking statements. Zenith undertakes no obligation to update such
forward-looking statements, which are subject to a number of risks and
uncertainties that could cause actual results to differ materially from those
projected. These risks and uncertainties include, but are not limited to the
following: 1) current unprecedented volatility in the financial markets,
including the duration of the crisis and the effectiveness of governmental
solutions; 2) current economic recession; 3) competition; 4) decreased payroll
levels of our customers; 5) medical cost trends; 6) regulatory restrictions on
investments; 7) changes in state and federal legislation and regulation; 8)
changes in interest rates causing fluctuations of investment income and fair
values of investments; 9) changes in the frequency and severity of claims and
catastrophes; 10) adequacy of loss reserves; 11) changing environment for
controlling medical, legal and rehabilitation costs, as well as fraud and abuse;
12) losses associated with any terrorist attacks that impact our workers`
compensation business in excess of our reinsurance protection; 13) losses caused
by nuclear, biological, chemical or radiological events whether or not there is
any applicable reinsurance protection; and 14) other risks detailed herein and
from time to time in Zenith`s reports and filings with the Securities and
Exchange Commission.

Zenith National Insurance Corp.
William J. Owen
Senior Vice President,
Investor Relations
818-676-3936

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