There are two coronary arteries, named after their crown-like arrangement around the heart, and they provide an important blood supply to meet the heart's enormous energy requirements for its constant contractile activity. There is a left and a right coronary artery, both of which originate from the aorta. Coronary artery endothelial cells (CAECs), which line the vessel wall, are continuously exposed to shear stresses that alter cell morphology and the production of endothelium-derived substances that regulate vasoconstriction and vessel growth. CAECs also modulate the expression of cell adhesion molecules to control and refine inflammatory responses and fibrinolysis. These physiological properties allow CAEC cultures to be widely used in the study of mechanisms of endothelial dysfunction, the pathogenesis of coronary artery disease and atherosclerosis, and in the development of new disease treatments.