HUMAN GENOME/AVENTIS BEHRING TO DEVELOP PLASMA PROTEIN.

Human Genome Sciences, Inc. (Nasdaq: HGSI) Rockville, Md., and Aventis Behring L.L.C., King of Prussia, Pa., have signed a development and commercialization agreement to co-develop and jointly market an Aventis Behring plasma protein product. This plasma protein, to be selected by mutual agreement of Aventis Behring and HGS, will use the multiple strengths and capabilities of both organizations to capitalize on the aligned interests of each company in albumin fusion technology.

Linking a therapeutic plasma protein with albumin may provide a number of product advantages, including the possibility of a longer acting form of the molecule for use in the human body, through extended circulating half life and consistent maintenance of therapeutic levels of the drug. The technology also offers manufacturing efficiencies in terms of production yields and ease of purification.

"We are delighted that our acquisition of Principia has led to a new relationship with Aventis Behring for the co-development of the next generation of a blood plasma protein. They are an ideal partner in the blood plasma area, bringing a proven team of scientists, with an extensive track record of success," said William A. Haseltine, Ph.D., chairman and CEO of Human Genome Sciences. "Together, our companies will use the expertise of Aventis Behring in this market, and the streamlined protein development organization of Human Genome Sciences, to deliver an albumin fusion plasma protein to patients in need."

"We are pleased that Aventis Behring's technology is at the forefront of a new research and development initiative. Partnering with Human Genome Sciences to develop an albumin fusion plasma protein makes sense as they share our vision of bringing this new technology to the people who need it most, our patients," said Dr. Ruedi Waeger, CEO of Aventis Behring. "Most importantly, our agreement with Human Genome Sciences will allow Aventis Behring to continue its mission to develop and deliver the highest quality, life-saving blood plasma proteins."

This technology was originally developed by Delta Biotechnology, a wholly owned subsidiary of Aventis Behring. For polypeptide applications, this technology has been licensed to Principia Pharmaceutical, a wholly owned subsidiary of Human Genome Sciences. Aventis Behring is a global leader in the development and marketing of plasma protein therapies and recombinant products.

Human Genome Sciences is a company with the mission to treat and cure disease by bringing new gene-based drugs to patients.

HGS and Human Genome Sciences are registered trademarks of Human Genome Sciences, Inc. For additional information on Human Genome Sciences, Inc., visit the company's web site at www.hgsi.com.

Delta Biotechnology Ltd. is based in Nottingham, United Kingdom and is a wholly owned subsidiary of Aventis Behring L.L.C. Delta Biotechnology is dedicated to the development of proprietary technologies for high yield recombinant expression and purification systems for therapeutic proteins. Delta Biotechnology has also established a technology and patent leadership position for albumin fusion proteins, a sophisticated molecular approach which may improve the clinical efficacy of many therapeutic proteins. For certain areas of application this technology was licensed to Principia Pharmaceutical, a wholly owned subsidiary of Human Genome Sciences.

Aventis Behring L.L.C. is a global leader in the therapeutic protein industry, providing a wide range of innovative, high-quality therapies and unique support services to patients worldwide. Aventis Behring is dedicated to the research and development of proteins from human blood plasma and emerging technologies. For more information about Aventis Behring, please visit www.aventisbehring.com.

Aventis Behring is the therapeutic protein business of Aventis Pharma AG. Aventis Pharma AG is the pharmaceutical subsidiary of Aventis S.A. Aventis (NYSE: AVE) is a world leader in life sciences. Focused on two core business areas -- pharmaceuticals and agriculture -- Aventis is dedicated to improving life through the discovery and development of innovative products in the fields of prescription drugs, vaccines, therapeutic proteins, crop production and protection, animal health and nutrition. With global corporate headquarters in Strasbourg, France, Aventis employs around 95,000 people in more than 120 countries and recorded pro forma sales in 1999 of 20.5 billion euros. Aventis was launched in December 1999 through the merger of Hoechst AG or Germany and Rhone-Poulenc SA of France.

For more information, visit http://www.aventis.com or call 610/878-4822.