The vascular endothelium plays a critical role in the preservation of normal vessel wall structure and function. In particular endothelial cells control vascular permeability, vessel tone, coagulation, fibrinolysis, and inflammatory responses. These functions are accomplished by production of a variety of biologically active substances. However, endothelial cell-mediated reactions may also lead to the development of pathological stages within the vessel wall. The current review is focused on endothelial cell metabolism in relationship to the development of atherosclerosis.