Sudden cardiac death constitutes the most devastating aspect of obstructive and non-obstructive hypertrophic cardiomyopathy. Loss of consciousness and family history of sudden cardiac death should alert the physician to the risk of sudden death. ECG, morphological and hemodynamic assessment, and exploration of central nervous activity are of little use in stratifying the risk of sudden cardiac death. Loss of consciousness associated with nonsustained ventricular tachycardia and inducible sustained ventricular arrhythmia identify patients at very high risk of sudden cardiac death. Nevertheless, many variable factors are involved in the pathophysiology of sudden cardiac death, and hence risk stratification of sudden cardiac death in patients with hypertrophic cardiomyopathy remains a very difficult clinical challenge.