Clinical data from Granulosa cell tumors (GCT) of the ovary were compared with data from 528 cases of malignant ovarian tumor in regard to symptomatology, treatment and prognosis. GCT are more frequent under the age of 30 and their biology requires a clinical separation from other feminizing mesenchymal tumors. Irregularities of uterine bleeding as a result of hormonal activity were the most frequent symptoms, explaining why their diagnosis is earlier than in ovarian cancer. The 5-year survival rates were similar when tumor stages were compared. GCT is associated with a frequency of late recurrences after 5, 10 or more years but a potential risk of malignancy is not related to clinical or histological criteria. Abdominal hysterectomy with bilateral salpingoophorectomy is standard treatment, whereas radiation and chemotherapy seem to be of little value.