Hoechst AG (German pronunciation: [ˈhøːçst] ^ⓘ) was a German chemicals, later life sciences, company that became Aventis Deutschland after its merger with France's Rhône-Poulenc S.A. in 1999. With the new company's 2004 merger with Sanofi-Synthélabo, it became a subsidiary of the resulting Sanofi-Aventis pharmaceuticals group.

The company was founded in 1863 as "Teerfarbenfabrik Meister, Lucius & Co." in Höchst, near Frankfurt and changed its name some years later to "Teerfarbenfabrik Meister Lucius & Brüning". In 1880, it became a stock company "Farbwerke vorm. Meister Lucius & Brüning AG". For the international market the name was simplified to "Farbwerke Hoechst AG". Until 1925, the Hoechst AG was independent. In 1916, the Hoechst AG was one of the co-founders of IG Farben, an advocacy group of Germany's chemicals industry to gain industrial power during and after World War I. In 1925, IG Farben turned from an advocacy group into the well-known conglomerate.

Various Hoechst facilities were bombed during the Oil Campaign of World War II. Its managers in charge were prosecuted along with other IG Farben managers — during the Nuremberg trials — in the IG Farben trial for their role in the exploitation of enslaved laborers and for testing drugs on concentration camp prisoners.

1951 — Hoechst AG was re-founded on December 7 in Frankfurt when IG Farben was split into its founder companies. The original capitalization of the company was 100,000 Deutsche Mark. By 1953, Hoechst had acquired parts of Knapsack-Griesheim, Kalle AG [de], Behring Werke, Wacker Chemie and Ruhr Chemie, among others.

1957 — Signed a technical cooperation contract with Handok Pharmaceuticals In South Korea

1964 — Handok Pharmaceuticals Joint Venture Partner In South Korea

1969 — Hoechst acquired Cassella.

1970 — Hoechst AG took over Berger, Jenson and Nicholson Ltd.