Women’s health advocates hope that artificial intelligence (AI) can advance our understanding of sex/gender health disparities, since medical research has historically focused on men. However, we lack deep insight into how AI techniques may either reify or destabilize human categories. This limits our understanding of how medical AI may impact conceptualizations of sex and gender, and by extension social equality, in and beyond medicine. To fill this gap, this project draws on feminist Science and Technology Studies to ask: how are categories and facts pertaining to sex and gender constructed and legitimized through the use of medical AI?