Background:Systemic lupus erythematosus(SLE) patients have a high prevalence of traditional risk factors for atherosclerosis. However, there is increasing evidence that traditional risk factors do not fully explain the atherosclerotic process in SLE.Endothelial dysfunction is the earliest key step of atherosclerosis.The aim of this study is to evaluate the endothelial dysfunction in premenopausal women with SLE and to determine whether there is any association between endothelial dysfunction and lupus–related factors. Methods:146 patients with lupus and 30 matched heathy controls were studied.Flow mediated dilatation(FMD) and carotid intima-media thickness(IMT) were measured.The patients were also evaluated with respect to their clinical and laboratory parameters,inflammatory mediators, disease treatment. Results:In SLE patients,FMD was significantly impaired compared to controls(9.7짹6.5 vs 12.1짹6.2%,P<0.05).The GTND did not differ in two groups.Within SLE patients,FMD was significantly associated with HDL cholesterol(r=-0.254,p=0.016),but negatively associated with IMT(r=-0.254,p=0.016)and ALT(r=-0.19,p=0.023).From the view point of inflammatory mediators associated with cardiovascular disease,FMD was higher in the lowest and middle tertiles of nitric oxide(NO) and osteoprotegerin(OPG) when compared with patients in the upper tertle of NO,OPG.In stepwise multiple regression analysis,IMT,presence of anticardiolipin antibody and serum OPG were independently associated with FMD(p=0.001,0.022,<0.001,respectively) Conclusion:This is the first study to examine endothelial dysfunction in premenopausal women with SLE in oriental persons.The endothelial dysfunction among lupus patients is associated with carotid IMT,anticardiolipin antibody and OPG..Our results might lead to potential interventions that may slow or even reverse the progression of atherosclerosis in SLE patients.