An excellent knowledge of histopathological risk factors of superficial bladder transitional cell carcinoma is mandatory to establish the prognosis of the disease. Presence or absence of carcinoma in situ (CIS) in superficial bladder cancer is one of the most powerful risk indicators. This study examines the usefulness of fluorescence photodetection of neoplastic urothelial foci in bladder cancer following intravesical instillation of delta-aminolevulinic acid (5-ALA). Following bladder instillation of an aqueous solution of 5-ALA in 43 cases, a Krypton ion laser and a Xenon arc-lamp were successively used as excitation source of the PPIX fluorescence. Tissular samples were respectively taken during bladder wall photodetection, either by the means of a video camera, or under direct endoscopic observation. A good correlation was observed between the fluorescence findings and the histopathological diagnosis. On a total of 298 biopsies, 49/110 carcinomatous lesions were detected by the fluorescence, whose more than 36% were CIS. PPIX induced fluorescence with topical bladder instillation of 5-ALA is an efficient and useful method of mapping the mucosa in bladder carcinoma. Moreover, in case of a multifocal disease, this method seems very helpful in finding and treating any residual malignant spots at the end of a transurethral bladder resection.