Plasma levels of human chorionic gonadotropin (hCG), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were studied in patients with epithelial ovarian carcinoma prior to and during chemotherapy. Blood samples were drawn for radioim-munoassay at monthly intervals. Plasma concentrations were compared to those of three different control groups: healthy post-menopausal women (PM), fertile women in the follicular phase of the menstrual cycle (FPh), and postmenopausal women with nongynecologic disseminated malignant disease (DMD). The hCG level was elevated in women with great tumor burden, such as large tumor volume, FIGO stage IV, and histologic type V. LH and FSH levels showed the reverse pattern. hCG concentration decreased during chemotherapy, whereas LH increased. Initial plasma concentrations were not found to have prognostic importance. We discuss the possibility that hCG is produced by the tumor, which stimulates steroid hormone production by the stroma, which, in turn, exerts negative feedback on FSH production by the pituitary. © 1990.