Estrogen receptor (ER) and progesterone receptor (PgR) were quantitated in benign and malignant human prostatic tissue by using radioligand binding assays (RBA) and enzyme-immunoassays (EIA). Using a hydroxylapatite exchange method for ER, little or no nuclear ER (ERN) could be detected, but with the EIA both cytosolic (ERC) and ERN were detected in almost all specimens, although in meager concentrations. Tissue from patients with carcinoma had significantly higher ERC concentrations than tissue from patients with benign disease. Specimens from estrogen-treated patients had significantly lower ERC:ERN ratios than those from untreated patients. Progesterone receptor was detected in virtually all specimens by both methods, at concentrations higher than those of ER. Carcinoma tissue with a high malignant involvement contained significantly less PgR than benign tissue. Using either method, the highest concentrations of PgR were observed in tissue from carcinoma patients treated with estrogen. Overall, the data suggest that although human prostatic tissue contains only modest amounts of ER, this is active in that treatment with estrogen promotes association of this receptor with the nuclear fraction and increases PgR content.