Argyrophilic nucleolar organizer regions (AgNORs) were examined histologically in cells of benign hyperplastic and cancerous human prostates. Individual dots of AgNORs inside nucleus that were stained as separate granules or as parts of clusters were counted as one, and the average number of dots per cell was obtained by counting 100 nuclei. The number in epithelial cells was similar to that in stromal cells of hyperplastic prostates. In cancerous prostates, the number was larger than in hyperplastic prostates and increased along with upgrading. The number in incidental cancers was smaller than in clinical cancers as compared with cells of the same Gleason pattern. Number correlated with T factor, but not with N and M factors. Response to treatment and cause-specific survival in stage D2 patients receiving endocrine therapy did not correlate with number, although a relationship between Gleason pattern and survival was shown in these patients. It was concluded that AgNORs might not be an indicator to predict prognosis after endocrine therapy, since a number of AgNORs did not influence response to the therapy.