In 5 intervention studies the beneficial effect of lipid lowering by antilipemic drugs on the course of atherosclerotic lesions has been shown by serial coronary angiography in patients with manifest coronary heart disease. The beneficial effect depended on the level of LDL and HDL cholesterol during drug therapy. This could not only be shown by coronary angiography but also by the frequency of clinical cardial events. The results of these studies indicate that the prognosis of patients with coronary heart disease depends on the LDL and HDL cholesterol concentrations during therapy and not on those before initiating antilipemic drug therapy. Therefore a consequent lipid-lowering therapy is necessary. The best prognosis was observed at LDL cholesterol concentrations lower than 100 mg/dl.