Objective To investigate the Effect of low density lipoprotein (LDL) on endothelial cell adhesion in shearstress and its relationship with lipid and filamentous actin (F-actin). Methods The endothelial cells (ECV-304) wereincubated with different concentrations of low density lipoprotein (0 mg/L, 50 mg/L,100 mg/L,150 mg/L) for 24h. Thereafter,the content of cholesterol ester in endothelial cells was assayed with High Performance Liquid Chromatography (HPLC).The lipid within endothelial cells was detected with oil red O. F-actin was examined with fluorescence staining ofrhodamine-phalloidin. After treated with LDL, endothelial cells were subjected to flow shear stress of 15Pa for 24h.Results Compared to control, LDL significantly increased the ester level in endothelial cells (80.3±1.5 μg/g, 115.5±2.2μg/g and 160.6±3.2 μg/g to control 61.3±1.6 μg/g, p<0.05). Observation by fluorescence microscopy showed that thefibers of F-actin in normal endothelial cells concentrated along the cell membrane and no dense fibers were observed inthe cytoplasm. The abnormal F-actin were appeared in LDL-treated endothelial cells, while most of the peripheral fibersdisappeared and dense stress fibers were observed in the cytoplasm with high dose LDL. After exposed to 1.5 Pa shearstress the conformance and the adhesion of endothelial cells which incubated with 150 mg/L LDL decreased comparingwith control. Conclusion LDL causes lipid accumulation and the cytoplasm damaged, which may relate to endothelialcell conformance and adhesion.