Résumé : Steroidogenic factor-1 (SF-1) protein expression was not observed in any form of endometriosis (peritoneal, ovarian, or deep infiltrating endometriosis), which suggests that SF-1 locally produced by endometrial or stromal cells may not play a major role in the development of endometriosis. However, the strong expression of SF-1 in cortical and medullary ovarian mesenchymatous cells may be capable of creating a favorable steroidogenic environment and the development of the disease. © 2011 by American Society for Reproductive Medicine.