We compared preoperative echograms and postoperative histological specimens from 16 patients who had undergone radical prostatectomy or radical cystourethrectomy to evaluate the correlation between the so-called capsular echogram obtained on transrectal ultrasonography and histology of the prostatic capsule. The capsular echogram corresponded to the periprostatic fatty tissue in all cases. In 10 of the 16 cases lateral ruptures of the capsular echogram were observed. Histologically, these ruptures corresponded to fibrous bundles in 6 of the 10 cases and to neurovascular bundles located close to the prostatic tissue in the other 4 cases. Because the prostatic glands, prostatic capsule, blood vessels and nerve fibers complicated the structure on the lateral sides near the apex, the borders of the prostatic gland were indistinct on the echograms.