One hundred and one cases of carotid atherosclerosis(CAS) were diagnosed by ultrasonography. The intermediate(IMT) of common carotid endomembrane in CAS group was much thicker than that in the healthy group(P < 0.01). There was no significant difference between the two groups in the peak velocity in systolic stage(MAX), the velocity in diastolic stage(MIN), resistance index(RI) and vessel size. The atheromatous plagues were usually flat plaques, seen at the bifurcation of common carotid artery. They belong to early pathological changes. It seems that the plaques don't affect MAX, MIN and RI of the common carotid artery.