After myocardial infarction, beta-blockers, aspirin and (in selected patients] ACE inhibitors all reduce substantially the risk of further myocardial infarction or coronary death. With regard to life-style changes, giving up cigarette smoking reduces coronary risk by about 50%. Weight reduction and regular exercise are advised, although the effect of these measures on prognosis is uncertain. Recently two major trials, the Scandinavian Simvastatin and West of Scotland Pravastatin studies, have radically changed ordinary medical practice. In these trials HMG CoA reductase inhibitor [statin) treatment reduced coronary events by 30-40%, reduced all-cause mortality, and proved safe and well-tolerated. The accepted policy now is to treat all patients with coronary heart disease, who have a cholesterol concentration 5.5 mmol/l or higher, with a statin. Where does this leave cholesterol-lowering dietary advice in secondary prevention? The benefits of statin treatment were attained by reducing serum cholesterol by an average of 25%. Diet change rarely attains such a fall in cholesterol and should therefore be used only as an adjunct to drug therapy. When recommending a lipid-lowering diet there is a danger that patients may be denied highly-effective drug treatment because of the 'threshold' effect. A decision on the need for cholesterol reduction should be made before diet change is advised. Once the decision is made the target is a 25% cholesterol reduction, which will require drug therapy in addition to diet changes.