Synchronous endometrioid carcinoma of the uterine corpus and ovary is an uncommon but well recognized event. Diagnosis as either a separate independent primary or as a metastatic tumor requires careful consideration of a number of gross and histological features. These features illustrate the criteria helpful in distinguishing independent primaries from metastatic carcinomas which have a different therapeutic implication. The possible link between fertility drugs and carcinogenesis still remains controversial. We report a case of a 52-year-old woman who came to our hospital with a cystic left ovarian mass (8 cm). Hysterectomy and bilateral salpingo-oophorecromy were carried out. Histological examinations showed well differentiated endometrioid ovarian cancer and well differentiated endometrioid endometrial cancer. The endometrial tumor was intramucosal without myometrial or vascular invasion and was associated with atypical complex hyperplasia. The woman had not been previously treated with ovulation induction drugs. She was free of recurrence two years after surgery. Patients with synchronous endometrioid tumors of the endometrium and ovary are generally younger than reported for either endometrial adenocarcinomas or ovarian adenocarcinomas. They tend to be low grade and early stage and are frequently associated with endometriosis. The prognosis of endometrioid type carcinomas is better than other histological types of carcinoma.