Arrowhead Receives and Responds to Notification of Minimum Stockholders` Equity Non-Compliance from the NASDAQ Stock Market

PASADENA, Calif.--(Business Wire)--
Arrowhead Research Corporation (NASDAQ:ARWR) announced that it received a
notification letter from The NASDAQ Stock Market ("NASDAQ") indicating that its
stockholders` equity, based on its Form 10-Q for the period ended March 31,
2009, does not comply with NASDAQ Marketplace Rule 4310(c)(3), which requires
companies listed on The NASDAQ Capital Market to maintain a minimum of $2.5
million in stockholders` equity. Today Arrowhead submitted a plan to regain and
sustain compliance with the minimum stockholder equity requirement. If accepted
by NASDAQ, the Company may be provided with up to 105 calendar days to
demonstrate compliance. The NASDAQ notification does not affect the listing of
Arrowhead`s common stock at this time.

Commenting on the receipt of the NASDAQ`s notification letter, Dr. Christopher
Anzalone, CEO of Arrowhead, stated, "We have prepared and submitted to NASDAQ a
plan to regain and sustain compliance with the exchange`s minimum stockholders`
equity requirement. We are taking action to strengthen our balance sheet to put
Arrowhead on a stronger financial footing and expect this will be reflected in
our results for the quarter ending June 30, 2009."

About Arrowhead Research Corporation

Arrowhead Research Corporation (www.arrowheadresearch.com) (NASDAQ:ARWR) is a
nanotechnology company commercializing new technologies in the areas of life
sciences, electronics, and energy. Arrowhead is seeking to build value for
shareholders through the progress of majority owned subsidiaries. Currently,
Arrowhead has four subsidiaries commercializing nanotech products and
applications and investments in two minority-owned subsidiaries.

Safe Harbor Statement under the Private Securities Litigation Reform Act of
1995:

This news release contains forward-looking statements within the meaning of the
"safe harbor" provisions of the Private Securities Litigation Reform Act of
1995. These statements are based upon our current expectations and speak only as
of the date hereof. Our actual results may differ materially and adversely from
those expressed in any forward-looking statements as a result of various factors
and uncertainties.For example, there can be no assurance that we will be able to
maintain our listing on any NASDAQ market, that our financial initiatives will
succeed in strengthening our balance sheet or that we will be able to continue
to operate as a going concern. Arrowhead Research Corporation's Annual Report on
Form 10-K and 10-K/A, recent and forthcoming Quarterly Reports on Form 10-Q and
10-Q/A, recent Current Reports on Forms 8-K and 8-K/A, our Registration
Statements on Form S-3, and other SEC filings discuss these and other important
risk factors that may affect our business, results of operations and financial
condition. We disclaim any intent to revise or update publicly any
forward-looking statements.

Investor Relations Contact:
Sanjay M. Hurry
The Piacente Group, Inc.
212-481-2050
sanjay@tpg-ir.com

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