The clinical course and histologic features of 118 granulosa cell tumors and 82 theca cell tumors were reviewed. Although the 2 cell types are related, important differences exist in their behavior. Theca cell tumors (TCTs) are virtually benign, while granulosa cell tumors (GCTs) exhibit less malignant activity than most ovarian carcinomas. Characteristically detected at an early stage, GCTs may recur locally years after the initial diagnosis. Survival figures depend on tumor stage. Recurrence of GCTs is associated with a high mortality rate. The cornerstone of treatment is total abdominal hysterectomy and bilateral salpingo-oophorectomy, regardless of age. Adjuvant radiation or chemotherapy may be helpful when lesions are higher than stage lai. Therapy for recurrence usually requires operative excision combined with radiation, chemotherapy, or both.