A retrospective study of 990 ovarian carcinomas treated at our hospital during the years 1945 through 1964 is presented. The study comprises serous, mucinous, endometrioid, undifferentiated and mesonephroid tumors. Histologic classification and clinical staging were performed according to the systems adopted by FIGO.Unilateral tumors had a significantly better prognosis than bilateral tumors, and the occurrence of ascites in Stage I was a bad prognostic sign. In Stages II and III, complete removal of all macroscopic tumor tissue was of great importance. For patients with potentially malignant tumors, survival curves showed a small, hut steady decline during the entire observation period up to 20 years after primary treatment, and no less than 15–25% of the patients died from cancer. Among the truly invasive carcinomas, mesonephroid tumors of clear-cell type had the best prognosis, and then endometrioid, mucinous, mesonephroid with tubular pattern, serous and undifferentiated tumors, in that order. Serous carcinomas had a great tendency to a protracted clinical course with late recurrences up to 20 years after primary treatment.