Aim To study the improved effect of Xuezhikang on endothelial function in patients with hyperlipoidemia. Methods Patients with hyperlipoidemia were randomized to placebo(n=28)or Xuezhikang 0.06 g daily(n=30) for 8 weeks.Brachial ultrasound was used to measure endothelium dependent flow mediated dilatation (FMD)and response to endothelium independent nitroglycerin. Serum lipid profile was determined enzymatically. Results Total and LDL cholesterol and TG levels were similar before randomization in both groups. With Xuezhikang,not with placebo, they decreased by 21.5%(P<0 01)and 28.2%(P<0 01)and 16.2%(P<0 01) respectively. FMD was unchanged with placebo,2.98±2.16 to 3.23±1.89,but increased with Xuezhikang, 2.86±1.59 to 6.47±2.72 (P<0 01). Responses to nitroglycerin were similar in the two groups. Conclusions Xuezhikang could markedly decrease serum TC and LDLC and TG concentration and improve endothelial function in patients with hyperlipoidemia.