Summary— Transitional cell carcinoma involving the prostate gland was studied in 27 patients. Three different groups were recognized on the basis of the clinical pattern and histological findings. Each group has a different prognosis and merits a different approach to treatment. Thus, stromal involvement of the prostate by transitional cell carcinoma is a sinister finding that requires radical treatment, whereas ductal involvement by either carcinoma in situor non-invasive papillary tumours can be managed less aggressively. This study emphasises that the present classification for these tumours is unsatisfactory and that adequate histopathological information is essential for their management.