615 urothelial bladder tumors are evaluated retrospectively after reclassification of histological and cytological specimens according to the recommendations of the World Health Organization (1973) and International Union Against Cancer (1974). The reason for a subdivision of the T1 category for exophytic noninfiltrating carcinomas is discussed. The importance of stage and grade is demonstrated as well as the different prognosis of patients with primary or recurrent tumors of the same T category. The results of the study demand a differentiated therapeutic regimen for urothelial bladder tumors.