Twenty-nine patients with clinical stage T1-2, NO, MO prostate carcinoma were treated by retropubic radical prostatectomy. Diagnosis was made by fine-needle aspiration biopsy from six to eight separate sectors of the prostate. At the time of biopsy, diagrams of the palpated organ were drawn, depicting the location of the lesion and the site of each biopsy. Without the examiners' knowledge of cytologic data, extirpated prostate glands were examined with whole organ histologic sections, and carcinomas were scored according to the method of Gleason. The location and extent of all typical and malignant foci were mapped on a standard diagram. The results of preoperative cytologic examination were compared with postoperative histopathologic findings, showing a tendency toward underestimation of both the extent and degree of differentiation of the carcinomas during cytologic examination. In no case were these parameters overestimated during cytologic examination. The Gleason score correlated well with the presence of capsular and seminal vesicle invasion.