The results of epidemiologic studies on the efficacy of different strategies of prevention or improvement of the prognosis of coronary artery disease are generally expressed in terms of percentage reduction of risk; for example, the treatment of hypercholesterolaemia reduces the risk of coronary death by 21%. In order to improve the assessment of the efficacy of these approaches the authors propose to take into account the number of subjects which needs to be treated each year to prevent one cardiovascular event more than the control group (for example, in hypercholesterolaemia, 1,736 patients). This number depends on the reduction of risk and also on the incidence of complications in the control group. Using this method, the authors classified different therapeutic strategies in order of their efficacy: thrombolytic therapy in the acute phase of myocardial infarction, then aortocoronary bypass grafting of left main coronary or triple vessel disease, secondary prevention with stopping smoking, and betablocker therapy. Finally, primary prevention with anti-smoking campaigns, treatment of hypertension and hypercholesterolemia. Based on this figure and knowing the annual cost of patient treatment, it is possible to calculate a cost-effectiveness ratio for each of these therapeutic interventions.