Rectus abdominis muscle is one of the rare localizations of endometriosis. In this report, our aim was to present a case in which endometrioma was localized in rectus abdominis muscle. A 33-year old patient who underwent cesarean section six years before, complained of a painful mass measuring 4 cm localized at superior of the right side of incision scar. The mass which was found to be inside of the rectus abdominis muscle was excised totally. There was no relationship between the mass and intra-abdominal viscera and subcutaneous tissue. The result of pathologic examination was endometriosis. Endometrioma should be considered at differential diagnosis of abdominal wall mass in women during reproductive age especially if there is a past history of surgical intervention and shows variations according to menstrual cycle.
Keywords: Endometriosis, rectus abdominis