Urothelial cancer of the bladder is a frequent disease, and urinary cytology often is used as a routine diagnostic tool. But this technique has an impaired sensitivity in low-grade tumours, and as a subjective method it is highly dependent on the experience of the cytologist. Here we present the technique of fluorescence cytology as an improvement of conventional cytology. This method is potentially able to compensate for the disadvantages of urinary cytology as it is an automated process that uses the principles of 5-Ala-induced photodynamic diagnosis (PDD).