The relative distribution of androgen (AR), progesterone (PR), and estrogen receptors (ER) was localized and estimated in human prostate tissue by immunohistochemistry in five normal tissue samples, in eight benign hyperplastic (BPH) samples, in nine primary cancers, and in seven prostate cancer metastases. Moreover, three prostatic cancer cell lines (LNCaP, DU 145, and PC 3) were analyzed. A comparison between the results obtained by radioligand binding assays and immunohistochemistry was performed for the AR and PR. Using immunohistochemistry, the AR was exclusively detected in the nuclei of both benign and malignant prostatic epithelial cells. The highest proportion of AR-positive cells was found in BPH and in prostate cancer metastases as compared with normal prostatic tissue. In a majority of the cases, the PR was only present in the nuclei of stromal cells. Benign hyperplastic prostates contained higher proportions of PR-positive cells as compared with primary carcinoma. PR was sparse in epithelial cells. ER-positive stromal cell nuclei were only detected in carcinomatous prostates. A few ER-positive epithelial cell nuclei were found in one sample each of a BPH and normal prostate. All cells from the androgen-dependent, LNCaP, cell line and a majority of the cells from the androgen-independent, DU 145, cell line were AR-positive. In contrast, the cells from the androgen-independent, PC 3, cell line were all AR-negative. All three cell lines were PR- and ER-negative. The radioligand binding technique detected the AR in extracts from both the cytosol and the nucleus. Again BPH contained higher amounts of AR as compared with normal prostatic tissue. The LNCaP cells contained high amounts of cytosolic AR while cells from the DU 145 and PC 3 cell lines lacked detectable AR as estimated by biochemical techniques. There seemed to be a discrepancy between biochemically measured and immunohistochemically estimated receptor content.