Aim To investigate the Association between endothelial progenitor cells(EPC) and the features of carotid atherosclerotic plaque.Methods Cerebral infarction patients with carotid atherosclerosis and healthy volunteers without carotid atherosclerosis were enrolled.Carotid color Doppler ultrasonography and head computed tomography(CT) or magnetic resonance imaging(MRI) were applied in all persons enrolled.According to clinical symptoms of carotid color Doppler ultrasonography,they were divided into three groups:soft plaque group,hard plaque group and control group.Blood 10 mL were drawn from ulnar vein.Mononuclear cells were isolated from peripheral blood by density gradient centrifugation and cultured on the twenty-four well fibronectin-coated cell dishes.Nonadherent cells were discarded on day 4 and culture medium was then changed.Attached cells were collected.EPCs were characterized as double positive for Dil-acLDL and FITC-UEA-Ⅰ by laser scanning confocal microscope(LSCM).EPCs adhesion,and proliferation and migration were assayed with adhesion assay,MTT assay and modified Boyden chamber assay,respectively.Results The numbers and adhesive capacity of EPCs in soft plaque group and hard plaque group were higher than those in control group.The numbers,adhesive capacity and migratory capacity of EPCs in soft plaque group were higher than those in hard plaque group.The proliferative capacity of EPCs in control group were higher than those in soft plaque group and hard plaque group.The proliferative capacity of EPCs in soft plaque group were higher than those in hard plaque group.The migratory capacity of EPCs in soft plaque group were higher than those in control group.Conclusion EPCs are associated with the features of carotid atherosclerotic plaque.