For this study a prostate gland was obtained by retropubic total prostatectomy performed on a seventy-six-year-old patient at Gunma University Hospital. A surgical pathologist separated the gland into peripheral and central portions which were clearly divided by a fibrous stroma. Histopathologic examination of each layer revealed different patterns of adenocarcinoma. The cytosol was incubated with [3H]R1881, [3H]estradiol, or [3H]R5020 in the presence or absence of 100-fold excess unlabeled competing, R1881, diethylstilbestrol, or R5020, respectively. In addition, to measure only androgen receptor all androgen tubes contained 1 X 10(-5) M triamcinolone acetonide. Using glycerol density gradient technique, concentrations of androgen, estrogen, and progestogen receptor were measured on both tissues. Specific receptor concentrations were determined by computation of the suppressible binding from the 8S region of the gradients. The ratio of the androgen receptor to progestogen receptor in the central zone was 1.5 to 2.0 while the same ratio in the peripheral zone was 0.3 to 0.5. Estrogen receptor could not be detected in either portion of this gland, possibly because the patient had received large amounts of diethylstilbestrol diphosphate prior to operation. This is the first report of varying hormone receptor profiles in different anatomic zones of the human prostate.