Objectives:  To conduct a cost-benefit assessment of prevention of sudden cardiac deaths with an implantable cardioverter defibrillator (ICD) versus amiodarone from the perspective of the health-care systems in the UK and France.Methods:  Course after implantation with an ICD or taking amiodarone was modeled using discrete event simulation; 1000 pairs of identical patients were simulated 100 times for each analysis. Rates of life-threatening arrhythmia and death from other causes were assumed identical, but the case fatality of arrhythmia and hospitalization differ between treatments. Rates were based on published data, primarily from the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT). Direct medical costs (in 2004 Euros) and lives saved were estimated over 5 years. The monetary value of a life (UK €2.1 million, France €2.0 million) was applied to this benefit and examined relative to the net investment required.Results:  ICDs decreased deaths during the 5 years from 37.0% to 29.7% at a net cost of €26,222 to €20,008 per patient, yielding cost-benefit ratios of 0.17 (UK) and 0.14 (France)—more than a 5 to 1 return on investment. Sensitivity analyses showed ICDs represent value for money whenever a life is valued at least at €274,000.Conclusion:  In these European countries where society values a life at more than €2 million, ICDs are a worthwhile investment compared with amiodarone for primary prevention of sudden cardiac deaths in patients with heart failure.