This study evaluated the use of transcranial Doppler (TCD) and duplex carotid ultrasound (DCU) to assess internal carotid artery (ICA) stenosis compared to angiography in 67 patients. Several TCD and DCU parameters including upstroke time fraction, peak systolic velocity, and common carotid artery asymmetry were predictive of >70% ICA stenosis on univariate analysis. Multivariate analysis found common carotid artery damping/asymmetry to have high odds of predicting severe stenosis. The study concludes that combined TCD and DCU can reliably determine ICA stenosis >70% and may provide physiological information beyond degree of stenosis.