Today, strokes represent one of the leading causes of death in America. Pathologic studies have shown that the majority of stroke patients have atherosclerotic disease of the carotid bifurcation or of the origin of the vertebral arteries. Because of the significant medical and socioeconomic impact of strokes, there has been great impetus in the past 20 years to develop safe, sensitive, and reproducible screening tests to detect atherosclerotic disease of the extracranial carotid circualation. Currently, duplex Doppler and color Doppler are the most widely employed noninvasive methods of evaluating the carotid artery. This paper reviews both of these modalities.