Jacques Tréfouël (9 November 1897, Le Raincy – 11 July 1977, Paris) was a French medical chemist.

For the next ten years, he served as laboratory chief at the Institute, during which time, he was involved in the synthesis and development of drugs such as stovarsol, orsanine, and rhodoquine.

In 1935, in collaboration with his wife, chemist Thérèse Tréfouël, and pharmacologists Daniel Bovet and Federico Nitti, he conducted research of prontosil, of which, they demonstrated that only a portion of the substance, named sulphanilamide, was active against streptococcus.

The group also showed sulphanilamide's effective action against other types of bacteria (meningococcus, pneumococcus, gonococcus, Friedlander's bacillus, etc.).

From 1940 to 1964 he served as director of the Institute, while still retaining his role as head of the medicinal chemistry laboratory.