The process of micturition is related to activation of the cardiovascular autonomic nervous system. Hypotension with bradycardia often occurs during or immediately after micturition. We experienced a case of sudden severe hypotension and bradycardia following urethral catheterization in a patient who underwent an urethral dilatation and transurethral resection of bladder tumor while under general anesthesia. The patient was treated with inotropics and intravenous fluids, and he recovered without any complications. The characteristics of this case are similar to the physiologic changes that occur in micturition syncope. Therefore, it is presumed that the autonomic reflex that was triggered by the urethral catheterization caused the hypotension and bradycardia.