OBJECTIVE This report retrospectively analyzes 106 cases of endometrioid carcinoma of the ovary treated at the National Cancer Institute of Milan from 1974 through December 1993. In 12 of the 106 cases (11.3%) a synchronous carcinoma of the uterine body was observed. METHODS Only patients who had previously untreated disease were included in the study. Patients with synchronous tumors were staged according to their ovarian cancer and treated according to the stage of that disease. RESULTS Thirty-nine patients (36.8%) had stage 1, 17 (16.0%) stage 11, 43 (40.6%) stage III, and 7 (6.6%) stage IV disease. Moderately plus poorly differentiated tumors were present in 76 of the 106 cases (71.7%). Considering the 67 patients with advanced disease, residual tumor was absent in 27 cases (40.3%), < or = 2 cm in 17 (25.4%), and > 2 cm in 23 (34.3%) cases. Systematic pelvic and para-aortic lymphadenectomy was performed in 60 patients (56.6%); selective sampling was carried out in 23 cases (21.7%). After surgery, 77 patients underwent various chemotherapy regimens. CONCLUSIONS Using univariate analysis, FIGO stage, tumor grade, residual disease after surgery, lymph node status, and platinum in the chemotherapy regimen significantly influenced 5-year survival. However, when all these variables were included in a multivariate analysis only FIGO stage still had a significant impact on survival. Survival analysis also showed a trend towards longer survival in patients with synchronous tumors.