ArcSight Elects Tom Reilly to Board of Directors

CUPERTINO, CA, Jun 19 (MARKET WIRE) --
ArcSight, Inc. (NASDAQ: ARST), today announced that Tom Reilly,
ArcSight's president and chief operating officer, has joined the
company's board of directors.

Mr. Reilly has served as the company's president since August 2007 and as
chief operating officer since November 2006. From April 2004 to November
2006, he was vice president of business information services of IBM. From
November 2000 until its acquisition in April 2004 by IBM, Mr. Reilly
served as chief executive officer of Trigo Technologies, Inc., a product
management software company. He holds a B.S. in mechanical engineering
from the University of California, Berkeley.

"We are pleased to welcome Tom Reilly to the Board," said Robert Shaw,
chairman and chief executive officer. "Tom's strategic operations
expertise and extensive industry knowledge expands the depth of the
ArcSight board, and we look forward to his continued contributions to the
company."

About ArcSight

ArcSight (NASDAQ: ARST) is a leading global provider of compliance and
security management solutions that protect enterprises and government
agencies. ArcSight helps customers comply with corporate and regulatory
policy, safeguard their assets and processes, and control risk. The
ArcSight platform collects and correlates user activity and event data
across the enterprise so that businesses can rapidly identify, prioritize,
and respond to compliance violations, policy breaches, cybersecurity
attacks, and insider threats. For more information, visit
www.arcsight.com. (ARST-IR)

Copyright2008 ArcSight, Inc. All rights reserved. ArcSight and the
ArcSight logo are trademarks of ArcSight, Inc.

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