The importance of identifying patients with carotid artery stenosis has attained greater significance in light of recent treatment trials of the efficacy of medical and surgical treatment of both symptomatic and asymptomatic carotid stenosis. Doppler and B-mode ultrasonography can accurately diagnose and quantify stenosis at the cervical carotid artery bifurcation. The development of duplex color-flow instruments has enhanced the sensitivity and specificity of this examination. Ultrasonography should be employed as an initial examination to identify patients with carotid artery stenosis and determine whether further evaluation or treatment is necessary.