A point-monitoring fluorescence diagnostic system based on a low-energy pulsed laser, fiber transmission optics, and an optical multichannel analyzer was used for diagnosis of patients with bladder malignancies. Twenty-four patients with bladder carcinoma, carcinoma in situ, and/or dysplasia were injected with hematoporphyrin derivative, Photofrin, 0.35 or 0.5 mg/kg body weight, forty-eight hours prior to the investigation. The ratio between the red sensitizer emission and the bluish tissue autofluorescence provided excellent demarcation between papillary tumors and normal bladder wall. Certain cases of dysplasia also could be differentiated from normal mucosa. Benign exophytic lesions such as malakoplakia appeared different from malignant tumors in fluorescence. Flat suspicious bladder mucosa such as seen in infectious diseases or after radiation therapy appeared normal on fluorescence.