Sudden unexplained death syndrome describes the death of apparently healthy individuals--usually young men--in whom postmortem examination does not reveal the cause of death. The victims are in apparently good health and usually die at night while sleeping. They die within minutes after the onset of agonal respiration. Patients who have been resuscitated were found to have ventricular fibrillation and inducible polymorphic ventricular tachycardia in the electrophysiologic laboratory. This syndrome has been most frequently described in young Southeast Asian men. In this review, the epidemiology, clinical and electrophysiologic manifestations, pathology and risk factors, prognosis, and treatments for sudden unexplained death syndrome are described.