Endothelial dysfunction represents an important step in the pathogenesis of atherosclerosis. All vascular risk factors can induce endothelial dysfunction, which in turn results in the loss of the protective effects of the endothelium culminating in the development of atherosclerosis. Dyslipidemia is a major vascular risk factor and is associated with endothelial dysfunction. Several studies showed that lipid-lowering agents exert beneficial effects on endothelial function in different populations at increased vascular risk, including patients without dyslipidemia. Therefore, other actions besides lipid-profile modification appear to be implicated in this benefit. However, it is unclear whether the improvement in endothelial function independently contributes to the vascular risk reduction during lipid-lowering treatment (e.g. with statins). It is also unclear whether the assessment of endothelial function would help identify patients who require more aggressive lipid-lowering treatment.