With the introduction of the terms atypical adenomatous hyperplasia (AAH) and prostatic intraepithelial neoplasia (PIN), the spectrum of prostatic diseases has been distinctly enlarged. With more sophisticated diagnostics, however, diagnostic and differential diagnostic problems grow more important. At the institute of pathology in Singen, this issue is reflected by the increasing use of the uropathologic consultation service since 1989. The purpose of this paper is to demonstrate typical diagnostic and differential diagnostic problems in the pathology of the prostate on the basis of this consultation service. 573 submitted prostatic cases were evaluated and the final diagnoses were compared to the preliminary diagnoses by the primary pathologist. Frequent differences could be detected in the 3 following groups: 1. Differentiation of sclerosing adenosis versus well differentiated adenocarcinoma 2. Differentiation of AAH versus well differentiated adenocarcinoma 3. Differentiation of high grade PIN versus poorly differentiated adenocarcinoma 4. Differentiation of glandular G II a versus G II b carcinomas. Possible decision guidelines are presented.