Damage to the endothelium is believed to be important in the development and progression of atherosclerosis. Consequently, vascular biologists are seeking good markers of endothelial cell function which hope to provide tools to dissect the role of these cells in disease. This review will examine a number of endothelial cell products (thrombomodulin, von Willebrand factor and soluble E-selectin) and discuss their value as markers of vascular integrity.