Spread beyond the capsule is a poor prognosis factor in clinically localized carcinomas of the prostate; preoperative diagnosis is difficult and clinical evaluation usually underestimates tumor spread. This prospective study was undertaken to confront results of the conventional workup (rectal examination, transrectal ultrasonography and PSA) and of CT scan and MRI findings with findings upon the pathologic study of operative specimens following radical prostatectomy. Results show that the conventional workup remains the diagnostic gold standard and that CT scan yields no additional information. Technically faultless MRI with sections in the three planes is a good means for analyzing the capsule of the prostate.