Baulieu began his scientific career with a strong focus on endocrinology and hormonal research. In 1963, he founded the Unit 33 research department at the French National Institute of Health and Medical Research (INSERM), entirely dedicated to hormone studies. Under his leadership, the department became one of Europe’s most innovative hubs for medical research. It was within this environment that Baulieu and his team made the discoveries that led to the development of mifepristone, a compound that would soon change the face of reproductive medicine.