Hormonal status was studied in 75 patients with malignant tumors of the ovaries. Blood levels of estradiol, estriol, progesterone and testosterone were assayed prior to treatment, at days 16-18 after surgery and at days 2-3 after a course of chemotherapy. Most of the patients, whatever their age or time onset of menopause, showed enhanced blood levels of estriol that remained virtually unchanged after surgery and that failed to respond to chemotherapy. No 17.beta.-estradiol or progesterone receptors could be found in any of the studied tumor tissue from patients with ovarian cancer.