Allied World Establishes Syndicate 2232 at Lloyd's of London

PEMBROKE, Bermuda, June 3, 2010 - Allied World Assurance Company Holdings, Ltd (NYSE: AWH) announced today
that it received approval from Lloyd's of London to establish a new
syndicate. Syndicate 2232, with the pseudonym AWH, will be fully operational
and writing business effective June 30, 2010.

(Logo: www.newscom.com/cgi-bin/prnh/20100519/LT07457LOGO-b )

Syndicate 2232 will be managed by Capita Managing Agency Limited, a
subsidiary of The Capita Group PLC, which is authorized by the Financial
Services Authority in the United Kingdom. The active underwriter will be
Darren Powell, currently Senior Vice President and manager of International
Property at Allied World Assurance Company (Reinsurance) Limited in London.

The syndicate will offer select product lines, which include
international property, general casualty, professional lines and
international treaty, targeted at key territories such as countries in Latin
America and the Asia Pacific region. Syndicate 2232's primary purpose is to
enhance Allied World's international platform and capabilities.

President and Chief Executive Officer Scott Carmilani commented, "As we
look to expand our global distribution network and further enhance our
existing business model, Lloyd's of London is a key partner in achieving
these strategic objectives. Its reputation as the world's leading provider of
insurance is unsurpassed and we are excited to join this elite market."

About Allied World Assurance Company

Allied World Assurance Company Holdings, Ltd, through its subsidiaries,
is a global provider of innovative property, casualty and specialty insurance
and reinsurance solutions, offering superior client service through offices
in Bermuda, Europe, Hong Kong, Singapore and the United States. Our insurance
and reinsurance subsidiaries are rated A (Excellent) by A.M. Best Company.
For further information on Allied World, please visit our website at
www.awac.com.

Cautionary Statement Regarding Forward-Looking Statements

Any forward-looking statements made in this press release reflect our
current views with respect to future events and financial performance and are
made pursuant to the safe harbor provisions of the Private Securities
Litigation Reform Act of 1995. Such statements involve risks and
uncertainties, which may cause actual results to differ materially from those
set forth in these statements. For example, our forward-looking statements
could be affected by pricing and policy term trends; increased competition;
the impact of acts of terrorism and acts of war; greater frequency or
severity of unpredictable catastrophic events; investigations of market
practices and related settlement terms; negative rating agency actions; the
adequacy of our loss reserves; the company or its subsidiaries becoming
subject to significant income taxes in the United States or elsewhere;
changes in regulations or tax laws; changes in the availability, cost or
quality of reinsurance or retrocessional coverage; adverse general economic
conditions; and judicial, legislative, political and other governmental
developments, as well as management's response to these factors, and other
factors identified in our filings with the U.S. Securities and Exchange
Commission. You are cautioned not to place undue reliance on these
forward-looking statements, which speak only as of the date on which they are
made. We are under no obligation (and expressly disclaim any such obligation)
to update or revise any forward-looking statement that may be made from time
to time, whether as a result of new information, future developments or
otherwise.

Media, Faye Cook, VP, Marketing & Communications, +1-441-278-5406, faye.cook at awac.com, or Investors, Keith J. Lennox, Investor Relations Officer, +1-646-794-0750, keith.lennox at awac.com