Abstract: ObjectiveTo explore the value of simvastatin in improving endothelial function in the patients with acute coronary syndromes in shorter time.Methods60 patients with acute coronary syndrome(acute myocardial infarction and unstable angina/non-ST elevation myocardial infarction) were randomized to be treated with placebo(n=30) or simvastatin 20 mg daily(n=30) for 3～5 d.At the admission and endpoint,Brachial ultrasound was used to measure endothelium-dependent flow-mediated dilatation(FMD) and response to endothelium-independent nitroglycerin. ResultsFMD was unchanged with placebo,but increased with simvasatin,from(2.65±2.95)% to(4.19±2.59)%(P=0.027).Responses to nitroglycerin were similar during the time course of the study in the 2 groups.The improvement of FMD was not correlated with the level of TC(R²=0.081,P=0.37),LDL-C(R²=0.056,P=0.46) or HDL-C(R²=0.073,P=0.40).ConclusionSimvastatin initiated early after acute coronary syndromes rapidly improves endothelial function in short course.No correlation has been detected between the pharmacological effects of simvastatin with the fall in TC and LDL-C.