Abstract: Objective To examine the protective effect and its mechanism of haw thorn flavone on human vascular endo-celial cells.Methods Original human umbilical vein endocelial cells(EC) were cultured,and the changes of cell morphology,cell grow condition,lactate dehydragenase (LDH) released from cells,monocyte(MC) adhesion to EC,and thiobarbituric acid-reaction substance (TBARS) were measured when EC was incubated with oxidzed low density lipoprotein (oxLDL,100 mg/1) in the presence or not of haw thorn flavone,as well as with single haw flavone at three different doses(25,50,100 mg/1).Results EC survive rate of oxLDL group was lower (P<0.01) and LDH release rate was higher(P<0.05) than those of normal control group.Haw thorn flavone could protect EC from damage caused by oxLDL.The EC survive rates of haw thorn flavone + oxLDL groups in three doses were higher(P<0.05),the LDH release rates,MC-EC sticking rates and TBARS were lower(P<0.05) in a dose-effect manner compared with those of oxLDL group,respectively.The MC-EC sticking rates of single haw flavone groups in medium and high dose were lower than those of normal control group(P<0.05).Conclusion Haw thorn flavone could effectively protect EC from damage induced by oxLDL,which was contributed to its antioxidation activity and direct work on EC.