Color duplex scanning is important method in diagnostics of carotid stenosis disease (CSD). This method is accurate in estimation of stenosis degree and plaque quality characteristics as potential source of embolus. It enable the approach to extracranial as mostly affected segments of carotid arteries, frequent follow up of asymptomatic clinical course of the disease and inspection in local chemodynamic flow parameters. Beside numerous advantages, in cases of severe degree stenosis of echolucent or heterogeneous calcificant plaques, estimation of stenosis degree is inaccurate and than the use maximal flow velocities for stenosis degree estimation is better. Unfortunately in this situation some local carotid changes like multiple carotid plaques, significant proximal or distal concomitant stenosis as well as some disease like arterial hypertension, aortic valve disease, arrhythmia absoluta etc. may over or underestimate the stenosis degree, and thus make impossible the right diagnosis.