Carotid ultrasound has traditionally been used to evaluate the presence of obstructive atherosclerosis in the setting of symptomatic cerebrovascular disease or asymptomatic carotid bruit. More recently, carotid ultrasound has been performed in epidemiologic studies to measure intima-media thickness and detect nonobstructive plaque to evaluate the relation of these findings to cardiovascular disease risk factors and cardiovascular disease morbidity and mortality. The detection of subclinical carotid atherosclerosis has the same value as coronary subclinical atherosclerosis to improve risk prediction and re-classification compared with conventional risk factors. The present chapter will focus on carotid ultrasound as an imaging biomarker of cardiovascular risk, diagnostic assessment in asymptomatic patients with known or suspected carotid stenosis or coronary artery disease, and follow-up in treated patients. Moreover, training and certification will be addressed.