Western medicine is seen as universally valid, but in reality it displays a wide range of national and local variability. Our paper focuses on one such case of local variation: the widespread use of progestins in France to treat various pre-menopausal conditions as well as for contraception. The case of progestins allows us to explore how specific styles of research may come to dominate a particular local medical culture, and how they are influenced by changing criteria of scientific validity and wider social relations. We argue that in the 1980s and 1990s a single prestigious research-oriented Parisian hospital service played a dominant role in the transformation of progestins into scientifically validated medical practice. This status was not called seriously into question until recently when foreign research on a different form of hormone therapy suggested that risk was associated with their use. We also propose that both the research around and medical use of progestins in France was shaped by the positive attitude of many French women, including feminists, to hormonal therapies and to the non-surgical specialty most closely associated with hormones, medical gynaecology.