Abstract: Objective To observe the effect of vitam in C(VC)and vitam in E(VE)on the ultrastructures of vascular endothelial cells(VECs)following oxidative in jury in vitro.Methods VEC scultured in vitro were divided in to normal control,H₂O₂ oxidative control,VC(100μmol/L)+H₂O₂,and VE(100μmol/L)+H₂O₂ groups.VECs were injured by H₂O₂ after they were incubated with different dosages of VC or VE for 24 hours.The morphological changes of VECs in each group were observed with the electronic mic roscope.Results The ultras tructures of VECs in the H₂O₂ control group were signif icantly different from that of the normal control.The cell surfaces were smooth with the losing of the distinctive cell processes and mic rovilli.The mitochondria in cytoplasm were damaged seriously and had dimappearance.The roughen-doplasmic reticula obviously dilated to big hollow vacuoles in shape.The quantities of lysosomes and endocellular pinocy totic vesic lesincreased.In a few endo the lial cells,swollen mitochond ria with invisible ridge and irregula rnucleus were seen.The chroma tin in nuclear was partly dissolved.In VC+H₂O₂ and VE+H₂O₂ groups,electron mic roscopic observation revealed that the ultras tructures of VECs were damageds lightly,most of cells in both groups had the same structures as in the normal control.The microvilli and cytop lasmic processes on the cell surface became common.The cellular organs in cytoplasm were normal.The abnormal nucleus were not seen and the nuclea membrane was intact,nuclear chromatin had normal distribution.Only a few cells hads lightly dilated roughendoplasmic reticula and unclear mitochondria.Conclusion To some extent,V C,V E can protect the ultra structures of VECs following oxidative in jury.