Sudden death is a frequent complication of heart failure occurring in 35 to 45 per cent of the cases. This multifactorial event may be of haemodynamic origin (acute heart failure, electro-mechanical dissociation) or, more often, of rhythmic origin (torsade de pointe, sustained ventricular tachycardia, ventricular fibrillation, bradycardia, asystole). Numerous structural, haemodynamic, metabolic, ionic, neurohormonal and iatrogenic factors facilitate ventricular hyperexcitability. The main predictive factors of sudden death in heart failure are the presence of coronary heart disease and of reduced left ventricular ejection fraction; the prognostic value of ventricular rhythm disorders is controverted. Prevention of sudden death begins with correcting those factors which facilitate disturbances in rhythm and conduction. Beta-blockers are effective in the post-infarction period, but there is no evidence that other drugs are useful. Identifying patients at high risk and determining the therapeutic approach that reduces this risk are still incompletely resolved problems.