We report the case of a 21-year-old male whose frequent episodes of loss of consciousness in the dental surgery culminated in the postponement of treatment, pending further investigation. The patient was referred to a cardiologist and submitted to head-up tilt testing, which evoked prolonged asystole, associated with loss of consciousness and mild generalized twitching, confirming a diagnosis of malignant vasovagal syncope. Before dental treatment could be completed, the patient was successfully treated with disopyramide and dual-chamber pacemaker implantation.