Endothelial dysfunction is a catastrophic condition caused by disruption of the equilibrium between vasodilatation and vasoconstriction. Endocan is a proteoglycan derived from vascular endothelium. Endocan can interact with biologically active molecules, and these active molecules are essential for the balance of many biological functions, including cell adhesion, migration, proliferation, and new blood vessel formation. Increased endocan levels cause atherosclerosis in hypertension and coronary artery disease. We aimed to present a review of the biological functions of the endocan and the prevention of atherosclerosis.