Sudden cardiac death describes the unexpected natural death from cardiac cause within a short time period from the onset of symptoms (usually one hour) in a person without any prior condition that would appear fatal. The mechanism is generally a malignant ventricular arrhythmia (ventricular tachycardia or fibrillation). Sudden death is a major public health problem as it accounts for 3 to 400,000 deaths annually in the United States. Risk factors, physiopathological mechanisms, disease states associated with sudden death, and primary and secondary prevention treatments are reviewed.