The 1990s saw another major structural transformation, with Bayer, like other companies, facing the challenge of globalization.
In the wake of the radical political changes that took place in Germany and eastern Europe after 1989, the company increased its focus on these promising markets. As early as 1992, Bayer broke ground on a new site in Bitterfeld in eastern Germany, where production of Aspirin? began in 1994.
The importance of North America to the Bayer Group continued to increase. In Canada Bayer acquired Toronto-based Polysar Rubber Corporation in 1990 – the most significant acquisition in the company's history up to that point. The transaction made Bayer the world's biggest supplier of raw materials for the rubber industry. The addition of a new indication (thrombosis prophylaxis) prompts the World Health Organization (WHO) to include acetylsalicylic acid, the active ingredient in Aspirin?, in its “List of essential medicines” for a second time. The active ingredient had already been listed as an “essential medicine” in 1977.
Under the leadership of Dr. Manfred Schneider, Bayer acquired the North American self-medication business of Sterling Winthrop in 1994 – a milestone in the company's history, as the acquisition also allowed the company to regain the rights to the "Bayer" company name in the United States. For the first time in 75 years, Bayer could operate in the United States under its own name and with the Bayer Cross as its corporate logo. In 1995 U.S.-based Miles Inc. was renamed Bayer Corporation.
To better equip itself for the challenges of the future, Bayer set up a third pharmaceutical research center, this time in Japan, in addition to the locations in Europe (Wuppertal) and North America (West Haven, Connecticut). In 1995 the research center of Japanese pharmaceutical subsidiary Bayer Yakuhin Ltd. was dedicated at Kansai Science City near Kyoto. This marked the basic completion of Bayer's Europe/North America/Japan "pharmaceutical research triad." In the years that followed, these operations were supplemented by alliances with numerous innovative biotechnology companies.
On June 3, 1996 Bayer’s capital stock is redenominated into shares of DM 5 par value instead of DM 50. Two years later on July 1, the existing par-value shares of Bayer AG’s capital stock are replaced by no-par shares.
To mark the 100th birthday of Aspirin? on March 6, professional mountaineers wrap Bayer’s former high-rise headquarters building in Leverkusen, transforming it into the world’s biggest Aspirin? pack and earning the company three entries in the Guinness Book of Records.
Acquisition of the polyols business of Lyondell Chemical Company, United States, makes Bayer the world’s biggest producer of raw materials for polyurethanes in 2000. Bayer acquires Aventis CropScience for €7.25 billion in 2001, making it a world leader in crop protection. On December 6, the company‘s management announces plans to establish independent operating subsidiaries under the umbrella of a management holding company.