Aventis, a new world leader in life sciences, was created today, December 15, 1999, following a meeting of Rhone-Poulenc shareholders who approved by an overwhelming majority (97.1%) the final steps required to complete the merger between Hoechst AG and Rhone-Poulenc S.A. .

All shares of Aventis will begin trading on the Paris and Frankfurt stock exchanges as of December 20, 1999 under the common symbol "AVE'' as well as on the New York Stock Exchange in the form of American Depository Shares.

In a joint statement, Jurgen Dormann, designated Chairman of Aventis and Jean-Rene Fourtou, designated Vice-Chairman of Aventis, commented: "Today Aventis becomes reality. We would like to acknowledge the confidence shown in us by our respective shareholders and, in addition, we want particularly to thank our 90,000 employees whose dedication in the past months has made possible the creation of a new world leader in life sciences. The work achieved over the past months means that Aventis is fully operational and ready to go.''

They added: "Aventis will benefit from great competitive assets: substantial research and development resources, a highly promising pipeline, among the most powerful sales and marketing capabilities in the world, and a number of recently launched innovative products, the full potential of which has still to be fully leveraged.''

Key resolutions approved

These included:

• The appointment of five members of the Supervisory Board of Aventis, nominated by Rhone-Poulenc: Jean-Marc Bruel, Serge Kampf, Didier Pineau-Valencienne, Michel Renault and Marc Vienot. The five members of the Board nominated by Hoechst have already been appointed. They are: Dr. Martin Fruhauf, Professor Hubert Markl, Dr. Gunter Metz, Miss Seham Razzouqi and Dr. Hans-Jurgen Schinzler.
• The contribution of the Hoechst shares and the Gallus shares tendered in connection with the public exchange offer and adoption of the related increase in capital stock.

The total number of Aventis shares outstanding after the shareholder vote approving the increase in capital stock is 778 million shares.

Building on Positions of Strength

Aventis brings together the innovative strength and global reach of Hoechst and Rhone-Poulenc. Each drawing on more than one hundred years of history, the combination of the two companies through a merger of equals has created a world leader in pharmaceuticals and agriculture. Through these two core businesses, Aventis aims to improve the quality of life around the world by providing leading edge answers to two fundamental human needs -- health and nutrition.

Incorporated in France, with corporate headquarters in Strasbourg, France, Aventis counts 90,000
employees in 150 countries worldwide.

Aventis has top rankings in both pharmaceuticals and agriculture and a research and development budget of some 2.8 billion euros, the largest in the industry.

Aventis Pharma
Headquartered in Frankfurt, Germany and with 1998 proforma sales of 13.1 billion euros, the pharmaceuticals business of Aventis comprises:
-- Aventis Pharma, combining the prescription pharmaceuticals businesses of Hoechst Marion Roussel and Rhone-Poulenc Rorer;
-- Aventis Pasteur, human vaccines (formerly Pasteur Merieux Connaught);
-- Aventis Behring, therapeutic proteins (formerly the 50/50 joint venture Centeon, owned by Hoechst and Rhone-Poulenc);
-- and diagnostics, through a 51.8% stake in Dade Behring.

Aventis Agriculture
Headquartered in Lyon, France, and with 1998 proforma sales of 4.7 billion euros, the agricultural arm of Aventis comprises three businesses:
-- Aventis CropScience (the combination of the crop protection, crop production and seeds businesses of Rhone-Poulenc Agro and AgrEvo, in which Schering AG will hold a 24% stake);
-- Aventis Animal Nutrition (nutritional feed additives);
-- Merial (animal health) - a 50/50 joint venture with Merck & Co.

Aventis S.A. 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 90,000 people in 150 countries and recorded pro forma sales in 1998 of euros 21 billion (US$21.3 billion).

Company news release
N2312