Abstract: Objective To study the changes of vascular endothelial dilation function in aged patients with systemic inflammatory reaction syndrome（SIRS）. Methods Eighty-two aged patients with SIRS were divided into survival group（n=58） and death group（n=24）.Twenty-two non-SIRS patients served as a control group.Their plasma levels of endothelin-1（ET-1）,C-reactive protein（CRP）,interleukin-1（IL-1） and TNF-α were measured.Endothelium-dependent vascular dilation function mediated by brachial artery and nitroglycerine was observed by high resolution ultrasonography. Results The plasma levels of TNF-α,ET-1,IL-1 and CRP were significantly higher in SIRS patients and survival group than in controls（P＜0.05）.The endothelium-dependent vascular dilation function mediated by brachial artery was significantly lower in SIRS patients than in controls（2.21±0.18 vs 2.80±0.21,P＜0.01） and in death group than in survival group,while the endothelium-dependent vascular dilation function mediated by nitroglycerine was significantly higher in SIRS patients than in controls（P＜0.01） and lower in death group than in survival group（P＜0.01）.The plasma levels of TNF-α,ET-1,IL-1 and CRP were negatively correlated with endothelium-dependent vascular dilation function（P＜0.01）. Conclusion The endothelium-dependent vascular dilation function of patients with SIRS is obviously injured,which is correlated with the severity of SIRS.