Endothelial dysfunction is the early and crucial state of atherosclerosis that is associated with a poor prognosis. Mechanistically, endothelial dysfunction is caused by reduced nitric oxide bioactivity. HMG-CoA reductase inhibitors (statins) effectively lower cholesterol plasma levels and profoundly decrease the cardiovascular risk of hypercholesterolemic patients. It is well established that statins improve endothelial dysfunction in those patients. The underlying mechanisms are less clear. It is thought that pleiotrophic, cholesterol-independent effects of statins such as increase of nitric oxide bioactivity and reduction of oxidative stress may contribute to the vasoprotective effects of statins. Therefore, it is speculated that statins, at least in part, improve endothelial function independent of plasma cholesterol concentrations and may thereby exert beneficial clinical effects. This notion of statins as general atheroprotective drugs has been underlined by in vitro experiments, animal studies and small clinical trials. However, large-scale clinical intervention studies are needed to confirm a positive influence of statins on endothelial dysfunction and cardiac event rates in normochlesterolemic patients. (c) 2002 Prous Science. All rights reserved.