Ninety-one patients underwent radical retropubic prostatectomy. Forty-three specimens were examined after limited sectioning (series 1) and 48 underwent whole organ serial step-sectioning at 5 mm intervals (series 2) of the removed prostate gland. The latter allowed a more extensive assessment of tumour localization, multicentricity, extension, pT-stage and grade. Eighty-eight percent of specimens in series 1 had free surgical margins compared with only 41% in series 2 (p = 0.00001). Preoperative tumour grading by fine-needle aspiration biopsy, TUR-chips or 1.2 mm core biopsies was in agreement with postoperative grading in the prostatectomy specimens in 48% of the cases in series 1 and 67% in series 2, respectively. In series 2, preoperative localization of the tumours by palpation was accurately assessed in 75% of cases when compared to the findings at step-sectioning. Sixty-eight percent of 40 eligible glands in series 2 contained multiple tumours. 12/13 cases of unifocal tumours (92%) were classified as large single tumours. The sections were divided into four peripheral and four central parts/octants, and the tumour localization was marked within these octants. The apical and middle third of the prostate contained tumour in all cases, whereas the basal (cranial part) was engaged in 35%. Small tumours were localized mainly in the periphery of the gland, with no significant difference between dorsal and ventral octants. However, large tumours were situated mainly in the dorsal peripheral octants, concomitant with an increased involvement of the ventral and central octants.(ABSTRACT TRUNCATED AT 250 WORDS)