Androgen receptors (AR) predominated (98%) in the cytosols of human ovarian carcinomas (n = 40), compared to estrogen (ER)-45%, and progestin (PgR)-53% receptors. The average age of the patients was 58 years. Serum levels of estradiol-17 beta (E2), testosterone (T), follicle stimulating hormone (FSH) and luteinizing hormone (LH) were within the normal range. One third of the cases showed a measurable aromatase activity, while in the majority of the cases this activity was undetectable. The distribution of PgR in the 40 tumors studied appeared to correlate with aromatase activity. The distribution of ER and AR did not differ significantly in aromatase positive and aromatase negative tumors. Interestingly the majority of aromatase positive cases were the endometrioid type of carcinomas. Patients with this type of ovarian carcinoma may probably benefit from anti-estrogen, progestin or aromatase inhibitor treatment. All tumors which were negative for aromatase activity contained AR. In these aromatase negative tumors androgens may not be further metabolized into estrogens and the tumor cells may be influenced by the androgens through the AR present in them. Anti androgen treatment could possibly benefit the patients with such tumors.