In invasively growing tumours of the urinary bladder specificity and sensitivity of the urine cytology are sufficiently high with 100 and 66%, respectively, it is, however, not successful. Endoscopy and histological ascertainment are now as ever prevailing (TUR). Cytology is indispensable to the diagnosis of the carcinoma in situ of the urinary bladder. In non-invasive urothelial carcinomas the classification of the WHO after Friedell stands the test. It is also shown a better correlation to the cytological findings which more frequently become positive with growing degree of malignity. High degree of malignity, multiple tumours and positive cytology are to be valuated as particular risk factors concerning frequent relapses and their appearance of invasively growing tumours. The domain of cytology is the control of the course with curative aim of patients who were operated on in order to sustain the organ. Relapses are frequently more dedifferentiated than the primary tumour so that the recidivation is often indicated cytologically. The endoscopic demonstration of the recidivation may still be absent at the beginning. Also for controls under local chemotherapy cytology stands the test, in which cases we may not sufficiently judge the value of this treatment method due to the small number of cases.