Sudden cardiac death (SCD) is responsible for 300,000-400,000 deaths per year with a recurrence rate of up to 40% in survivors within the first 2 years. SCD often occurs in patients with chronic coronary artery disease, which is manifested by myocardial infarction and left ventricular dysfunction but is infrequently associated with acute infarction. SCD may be the initial symptom of coronary artery disease. Primary or rapid ventricular tachycardia are the most common arrhythmic causes of SCD. Endocardial mapping studies during electrophysiological study have shown areas of slowed conduction with abnormal endocardial electrograms in SCD patients with moderately damaged ventricles. SCD increases with age and occurs more frequently in men with coronary artery disease as a significant risk factor. Complex ventricular ectopy, once thought of as an independent risk factor, is not as good a predictor as poor left ventricular function for recurrence of SCD. While signal-averaged electrocardiograms can identify patients with slowed conduction, their positive predictive value for SCD is poor. Initial evaluation should be aimed at the identification of ischemia, since those patients with SCD and acute myocardial infarction do well when treated for their ischemia. The arrhythmias that are inducible during electrophysiological study are rapid and poorly tolerated. Patients with inducible ventricular tachycardia who are rendered noninducible pharmacologically have a good prognosis, whereas those who are still inducible or have no inducible arrhythmias have a high recurrence rate of SCD and should be considered for subendocardial resection when appropriate or for placement of an implantable defibrillator.