Objective To investigate the significance of intravascular ultrasound (IVUS) in diagnosis and treatment of carotid stenosis.Methods IVUS was performed before and after carotid arterial stenting (CAS) in 12 patients with moderate or severe carotid stenosis,admitted to our hospital from July 2014 to April 2016 and diagnosed by digital subtraction angiography (DSA).The severity of carotid stenosis,expansion and adherence of the stent were observed,respectively.Results DSA indicated 17 vessels having pathological changes,including 4 (23.5％) eccentric lesions and 13 (76.5％) concentric lesions;IVUS indicated 23 vessels having pathological changes,including 13 (56.5％) eccentric lesions and 10 (43.5％) concentric lesions;the rate of eccentric plaque detected by IVUS was significantly higher than that by DSA (P＜0.05).The carotid diameter stenosis degree measured by DSA was smaller than the stenosis degree by IVUS (P＜0.05).In 4 patients underwent CAS,DSA showed that the residual stenosis was more than 30％,and IVUS showed stent underexpansion or poor adherence;in other 5 patients undewent CAS,IVUS showed poor stent symmetry,however,IVUS showed that the stent expansion,symmetry and adherence became better after the balloon expansion.Conclusion IVUS is useful for evaluation before and after stenting in patients with moderate or severe carotid stenosis.