This study was designed to evaluate the efficacy of local block of the obturator nerve to avoid it's stimulation during transurethral resection (TUR) or tumors localised on the lateral bladder wall. Forty-five patients were studied, in whom the TUR operations were performed under spinal anaesthesia. The patients were divided into two groups: in the first group a local block of the obturator nerve was done, while the second group served as controls, and the stimulation of the nerve was avoided by reduction of the electrocoagulation voltage, incomplete bladder filling and resections of smaller ships. In the first group no stimulation was observed while in 5 patients of the second group was not possible to totally resect the tumor due to the persistent stimulation of the obturator nerve. In conclusion the local block of the obturator nerve is an effective method to avoid it's stimulation, easily performed and without complications.