FOR IMMEDIATE RELEASE               CONTACT:    Josh Schroeter (media)
Monday, April 29, 2002                          206.389.4335
                                                John Calhoun (investors)
                                                206.389.4361


                  Immunex Announces Settlement Of Certain
               Litigations Relating To Merger With Amgen Inc.

SEATTLE, WA - Immunex Corporation (Nasdaq: IMNX) announced today the
settlement, which is subject to court approval among other things, of three
lawsuits against Immunex and certain of its directors and officers relating
to the proposed acquisition of Immunex by Amgen Inc.: (i) a suit filed by
David Osher, on behalf of a class of Immunex shareholders, against Immunex,
all members of the Immunex board of directors, Wyeth and Amgen; (ii) a suit
filed by Adele Brody, on behalf of a class of Immunex shareholders, against
Immunex, Wyeth, all members of the Immunex board of directors and the
marital community of each named individual; and (iii) a suit filed by Edwin
Weiner, on behalf of a class of Immunex shareholders, against Immunex,
against Immunex, Wyeth, all members of the Immunex board of directors and
the marital community of each named individual.

In connection with the settlement, (i) Immunex and Amgen agreed to reduce
the termination fee payable by Immunex or Amgen under certain circumstances
set forth in the Amended and Restated Agreement and Plan of Merger among
Immunex, Amgen and a wholly-owned subsidiary of Amgen by $20 million, (ii)
Immunex obtained an updated opinion from Merrill Lynch, Pierce, Fenner &
Smith Incorporated regarding the fairness of the merger consideration from
a financial point of view to be received by Immunex shareholders, and (iii)
Immunex agreed to provide certain additional disclosures regarding the
merger in a Current Report on Form 8-K, which is being filed with the
Securities and Exchange Commission today.

On December 17, 2001, Immunex agreed to be acquired by Amgen. The
acquisition will merge Immunex, one of the fastest growing biotechnology
companies in the industry, with Amgen, the largest biotechnology company.
Pending required shareholder approval for both companies, and approval by
regulatory authorities, the transaction is expected to be completed as
early as June 2002. Shareholder meetings for both companies are scheduled
to occur on May 16, 2002.

Immunex Corporation is a leading biopharmaceutical company dedicated to
improving lives through immune system science innovations.

Note: Except for the historical information contained herein, this news
release contains forward-looking statements that involve substantial risks
and uncertainties. Among the factors that could cause actual results or
timelines to differ materially are risks associated with research and
clinical development, regulatory approvals, our supply capabilities and
reliance on third-party manufacturers, product commercialization,
competition, litigation and other risk factors listed from time to time in
reports filed by Immunex with the Securities and Exchange Commission,
including but not limited to risks described under the caption "Important
Factors That May Affect Our Business, Our Results of Operation and Our
Stock Price" within our most recently filed Form 10-K. The forward-looking
statements contained in this news release represent our judgment as of the
date of this release. Immunex undertakes no obligation to publicly update
any forward-looking statements. An electronic version of this news
release-as well as additional information about Immunex of interest to
investors, customer, future employees and patients-is available on the
Immunex home page at www.immunex.com.

Where you can find Additional Information about the Acquisition:
In connection with the proposed acquisition, Immunex and Amgen filed with
the Securities and Exchange Commission on March 22, 2002, their joint proxy
statement/prospectus that contains important information about the merger.
Investors and security holders of Immunex and Amgen are urged to read the
joint proxy statement/prospectus filed with the Securities and Exchange
Commission on March 22, 2002, and any other relevant materials filed by
Immunex or Amgen because they contain, or will contain, important
information about Immunex, Amgen and the acquisition. The joint proxy
statement/prospectus filed with the Securities and Exchange Commission on
March 22, 2002, other relevant materials and any other documents filed, or
to be filed, by Immunex or Amgen with the Securities and Exchange
Commission, may be obtained free of charge at the Securities and Exchange
Commission's web site at www.sec.gov. In addition, investors and security
holders may obtain free copies of the documents filed with the Securities
and Exchange Commission by Immunex by contacting Immunex Corporation, 51
University Street, Seattle, WA 98101, Attn: Investor Relations. Investors
and security holders may obtain free copies of the documents filed with the
Securities and Exchange Commission by Amgen by directing a request to:
Amgen Inc., One Amgen Center Drive, Thousand Oaks, CA 91320, Attn: Investor
Relations. Investors and security holders are urged to read the joint proxy
statement/prospectus filed with the Securities and Exchange Commission on
March 22, 2002 and any other relevant materials filed by Immunex or Amgen
before making any voting or investment decision with respect to the
acquisition. Immunex, Amgen and their respective executive officers and
directors may be deemed to be participants in the solicitation of proxies
from the shareholders of Immunex and Amgen in favor of the merger.
Information about the executive officers and directors of Immunex and their
ownership of Immunex common stock, and information about the executive
officers and directors of Amgen and their ownership of Amgen common stock
is set forth in the joint proxy statement/prospectus for Immunex's annual
meeting of shareholders and Amgen's annual meeting of stockholders, which
has been filed with the Securities and Exchange Commission. Investors and
security holders may obtain more detailed information regarding the direct
and indirect interests of Immunex, Amgen and their respective executive
officers and directors in the merger by reading the joint proxy
statement/prospectus regarding the acquisition.

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