Aim: They presented the results of the clinical trial conducted in Russia concerning the diagnostic efficacy of Hexasens drug - the photosensitizer based on hexyl ester of 5-aminolevulinic acid for the fluorescence diagnosis of bladder cancer. Materials and Methods: 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 diagnosed with bladder cancer in T1N0M0 stage. Fluorescence diagnosis was carried out for 1 h after the intravesical introduction of 0.2% solution (50 mL or 100 mg) of Hexasens drug (FSUE "SSC NIOPIK," Russia). Results and Discussion: The results of the fluorescence diagnosis were compared with the results of the standard routine cystoscopy. They showed that the performance of fluorescent diagnosis (FD) allowed to improve diagnostic sensitivity by 13.2% as compared to standard cystoscopy (from 86.8% to 100%), the diagnosis accuracy increased by 8.8% (from 91.2% to 100%) and a negative predictive value increased by 20.9% (from 79.1% to 100%). During the carrying out of fluorescence diagnosis, 8 patients (15.0%) of 53 ones also revealed 14 fluorescing foci not identified in white light, in which the tumorous process was confirmed during morphological study. Conclusion: The introduction of Hexasens solution into a bladder and the carrying out of an FD was not accompanied by the development of any adverse reactions. Patients had a subjective discomfort only during a prolonged exposure of the drug solution in a bladder (up to 2 h). The developed set of methods is recommended for the use in clinical practice. © 2018 Drug Invention Today.