The coexistence of carcinoma in the endometrium and ovary is a relatively uncommon but not rare occurrence. In general it has not been possible to determine which, if any, of these tumors represent metastases from endometrium or ovary or separate primary neoplasms, and gynecologists are unable to agree upon appropriate therapy. Twenty-four women with synchronous carcinomas of the ovary and endometrium in whom disease was confined to the pelvis, diagnosed at the Milton S. Hershey Medical Center between 1970 and 1982, were identified. Thirteen women had typical endometrial adenocarcinoma and endometrioid carcinoma of the ovary (Group A), two had unusual variants of endometrial carcinoma and a similar appearing tumor in the ovary (Group B), and nine had typical endometrial adenocarcinoma with carcinomas in the ovary of differing histologic appearance (Group C). There was no significant difference in survival between women in Groups A and C (77 and 56%, respectively, mean follow-up approximately 40 months). However, deep myometrial invasion (outer third) provided a statistically significant indicator of poor prognosis (77% with deep invasion vs 17% with superficial invasion recurred or died of disease P less than 0.05, chi 2 test).