Accessory ovary, described as extra ovary either adjacent or connected to normal ovaries, is a rare gynecological anomaly. Accessory ovaries may develop secondary to embryogenetic abnormalities, or to damage of normal ovaries due to inflammation or surgery. It is usually asymptomatic and defined incidentally. We report a rare case with endometriosis in accessory ovary, which was operated with diagnosis of ovarian cyst and myoma uteri.