Two cases of endometriosis infiltrating the round ligament and associated with an inguinal hernia are presented. The initial diagnosis was irreducible hernia, since this rare association often causes unusual preoperative symptoms and diagnostic problems. Diagnosis is frequently made by histologic examination. Surgery is the treatment of choice both for hernia and for endometriosis, and is locally curative. However, in a fertile woman with a painful mass in the inguinal region the possibility of endometriosis should be considered, and if suspected at inguinal exploration a laparoscopy should be made to rule out the presence of intraperitoneal endometriosis.