To determine the predictive accuracy of Doppler and real-time ultrasound studies, continuous-wave Doppler (CWD) and B-mode real-time ultrasound (RTU) studies of the carotid bifurcation were compared in 50 consecutive patients before cervicocranial arteriography. Four categories of CWD results were formed according to the severity of stenosis. Except for mild to moderate stenosis, there was a high degree of agreement (87.5% to 98.1%) between CWD results and arteriographic diagnosis. Of the arteries classified as normal on RTU study, 95.5% were arteriographically normal; of those classified as abnormal, 94.9% were abnormal on arteriography. In 94.7% of the cases in which RTU demonstrated a possible ulcer, the diagnosis was confirmed by arteriography.