Elevated serum cholesterol level has a causal role in the genesis of coronary atherosclerosis and causes plaque activation because it leads to plaque rupture, increases thrombus formation and adversely influences the function of endothelial cells. In patients with evidence of coronary heart disease (angina pectoris, previous myocardial infarction or previous coronary revascularization) the overall effect of cholesterol reduction therapy on the progression of lesions is modest. Nevertheless, the results of secondary prevention trials provide evidence that a reduction in the level of cholesterol leads to a significant decrease in the rate of cardiovascular events, in the rate of new procedures of revascularization by means of coronary surgery or angioplasty, in the coronary-heart-disease-mortality and in the non-coronary-heart-disease mortality. These effects probably mean some benefit on function, vulnerability and thrombogenicity of the plaque. In patients with previous revascularization procedures interest of secondary prevention by means of cholesterol lowering must be special, because in them the probability of long-term success should be optimized for the maximum patient benefit and the best use of health-care resources.