Photodynamic diagnostics of bladder tumors. Approximately 18,000 new cases of urothelial cancer of the bladder occur annually, making it the most frequent urogenital neoplasia representing nearly 4% of all malignomas. Tumor stage defines two subgroups requiring specific therapeutic approaches and implying distinct prognoses. Non-muscle-invasive urothelial cancer recurs frequently and occasionally progresses to muscle-invasive stages. Remnant tumor after initial resection is seen as one major factor in high recurrence rates. Although photodynamic diagnostics improving detection and increasing recurrence-free survival has been introduced to broad application, it has yet not been established as standard procedure. This article reviews the current literature and discusses controversial aspects.