This study was undertaken to investigate the correlation of the enhancement degree on contrast-enhanced ultrasound (CEUS) with the histopathology of carotid plaques and the serum high sensitive C-reactive protein (hs-CRP) levels in patients undergoing carotid endarterectomy (CEA).Carotid CEUS was performed preoperatively in 115 patients who would undergo CEA,and the enhancement degree of the carotid plaques was evaluated by both the visual semiquantitative analysis and the quantitative time-intensity curve analysis.Serum hs-CRP levels were detected using the particle-enhanced immunoturbidimetric assay also before the operation.Additionally,the carotid plaque samples were subjected to histopathological examination postoperatively.The density of neovessels and the number of macrophages in the plaques were assessed by immunohistochemistry.The results showed that among the 115 patients,grade 0 plaque contrast enhancement was noted in 35 patients,grade 1 in 48 patients and grade 2 in 32 patients.The degree of plaque enhancement,the density ofneovessels,the number of macrophages,and the hs-CRP levels were highest in the grade 2 patients.Correlation analysis showed that the enhancement degree of the carotid plaques was closely related to the immunohistochemical parameters of the plaques and the serum hs-CRP levels.It was suggested that the carotid plaque enhancement on CEUS can be used to evaluate the vulnerability of carotid plaques.