One of the principle aims in the assessment of the patient with hypertrophic cardiomyopathy is assessment of risk for sudden cardiac death. Conventional risk stratification is reviewed together with other non-invasive techniques such as exercise physiology; the signal averaged electrocardiogram and heart rate variability. The role of arrhythmias in the pathogenesis of sudden cardiac death in hypertrophic cardiomyopathy is reviewed together with the role of programmed ventricular stimulation. A novel electrophysiological technique is described in detail which aims to measure the electrophysiological effects of myocardial disarray and seems safer and more sensitive and specific than conventional electrophysiological techniques. Current therapeutic strategies are discussed including the role of drugs, the implantable cardioverter defibrillator, surgery and dual chamber pacing.