This study was performed as a clinical trial conducted in Russia concerning the diagnostic efficacy of Hexasens drug. The photosensitizer based on hexyl ester of 5-aminolevulinic acid was used for the fluorescence diagnosis of bladder cancer. The study was conducted in 2015-2016 on the basis of the City Clinical Hospital No. 40 (Moscow, Russia). 53 patients were involved into study and were diagnosed as bladder cancer in T1N0M0 stage. Fluorescence diagnosis was carried out for 1 hour after the intravesical induction of 0.2% solution (50 mL or 100 mg) of Hexasens drug (FSUE “SSC NIOPIK”, Russia). The results of the fluorescence diagnosis were compared with the results of the standard routine cystoscopy. The found results showed that the performance of fluorescent diagnostics (FD) led to improve diagnostic sensitivity as 13.2% compared to standard cystoscopy (from 86.8% to 100%); the diagnosis accuracy increased as 8.8% (from 91.2% to 100%) and a negative predictive value increased as 20.9% (from 79.1% to 100%). During the carrying out of fluorescence diagnosis, 8 patients (15.0%) out of 53 ones also revealed 14 fluorescing foci that not identified in white light, in which the tumorous process in them was confirmed during morphological study. The induction of Hexasens solution into a bladder and the carrying out of a fluorescent diagnosis was not accompanied by the development of any adverse reactions. Patients showed a subjective discomfort only during a prolonged exposure of the drug solution in a bladder (up to 2 hours). The developed diagnosis methods is recommended for the applying in advanced clinical diagnosis. © 2017 Slovokhodov Egor Konstantinovich et al.