The carotid artery is the main artery leading to the head and face of the body, and it supplies 85% of the blood to the brain tissue in normal times. Hypertension and atherosclerosis can directly attack the carotid artery, especially the bifurcation of the common carotid artery and the beginning of the internal carotid artery, where the blood flow easily forms vortex due to the hemodynamics. Carotid artery stenosis is mainly caused by the formation of atherosclerotic plaque at the bifurcation of the carotid artery. Strokes are caused by narrowing of the carotid artery that reduces cerebral blood flow below a critical state, or by the dislodgement of plaque fragments (so-called thrombi) that drift with blood flow to the brain and block larger cerebral arteries. High risk factors for plaque formation include smoking, hypertension, hyperlipidemia, diabetes and obesity, and age over 50 years. The most serious consequence of carotid artery stenosis is stroke, an acute cerebrovascular disease. Prevention is mainly to avoid the above factors. If carotid stenosis is more than 50% and clinically symptomatic, aggressive surgery, i.e. carotid endarterectomy (CEA), should be performed.