Aim Aim To explore the effects of two different doses of simvastatin (10 mg,20 mg/day) on vascular endothelial function of patients with coronary heart disease(CHD). Methods Totally 66 patients with CHD were included and randomly divided into: control group and simvatatin groups of different dose groups(10 mg/day,20 mg/day),22 patients in each group.The endothelial dependent flux modulated dilation(FMD) of brachial artery was measured by ultrasound technique before and after 8 weeks treatment.At the same time,we also examined the changes of the serum levels of lipids. Results After 8 weeks treatment,2 simvastatin groups(10 mg,20 mg) apparently reduced the serum level of TC(18.3%,29.3%,respectively) and the serum level of LDLC(25.3%,35.4%,respectively).The values of P between different dose groups comparison were all less than 0.05.The serum levels of lipids in control group did not significantly change after therapy.The values of FMD apparently increased in simvastatin groups(10 mg: 3.51%±4.03% vs 7.46%±5.90%;20 mg: 3.89%±3.97% vs(7.98%)±6.16%;p<0.01).But there was no statistic difference between them.The increase of FMD did not relate to the changes of TC and LDLC level in the serum.Although the value of FMD slightly increased in control group,it had no statistic significance.There was no significant change of vasodilation responding to nitroglycerin and brachial diameter in all groups after simvastatin therapy. Conclusion Different doses of simvastatin(10 mg,20 mg) can obviously improve the vascular endothelial function of patients with CHD in 8 weeks.But there is no significant changes between two different doses and it may not relate to lipid-lowering action.