Objective: to comparе the safety and efficacy of the new method of en-bloc transurethral resection (TUR) and conventional TUR in management of primary non-muscle-invasive bladder cancer, and investigate long-term effects on tumour recurrence and progression.Materials and methods. A total of 914 patients with primary non-muscle-invasive bladder cancer were treated using TUR of bladder at the Minsk City Clinical Oncologic Dispensary in 2005 to 2016. For final analysis the data was underwent many-stage random sampling. Randomization was stratified according to sex and age, category T, tumour grade, EORTC risk groups. In total, 273 patients were selected: 136 in the new method of en-bloc TUR group (a study group) and 137 in the conventional TUR group (a control group). The new method of en-bloc TUR is based on using impulses of high-frequency current applied to the active electrode of the resectoscope. The impulse sequence and individual impulse duration within the interval from 0.1 to 1 second are controlled in the course of the operation. Five-year follow-up data of operative management were analyzed.Results. In event of the new method of en-bloc TUR there were no perioperative complications and no cases of conversion to conventional TUR. Postoperative complications were less frequently observed in the new method group compared with conventional TUR group. There were significant differences with major priority to the new method of en-bloc TUR in median time to recurrence (р = 0.032) and progression (р = 0.001), 5-year survival to recurrence (р = 0.0001) and progression (р = 0.001), 5-year cancer-specific survival (р = 0.033) and overall survival (р = 0.045) of patients.Conclusion. The new method of en-bloc TUR of non-muscle-invasive bladder cancer was more effective than conventional TUR in reducing rates of intraand postoperative complications, and at the same time was applicable in all clinical cases, regardless of the tumor location in the bladder lumen, its size, vascularization, and growth pattern. The new method of en-bloc TUR also significantly improved the long-term cancer treatment results in patients with primary non-muscle-invasive bladder cancer.