Abstract: Objective To investigate the effect of Sini decoction(SND) in preventing vascular restenosis and protecting against oxidative stress after rabbit iliac artery balloon injury.Methods Twenty-four male New Zealand albino rabbits were equally randomized into control group,model group and SND group.Rabbits in the control group were fed with common forage,and those in the model and SND groups with high-fat diet.Two weeks later,the iliac arteries of the rabbits in the latter two groups were subjected to balloon injury.Four weeks after the operation,the rabbits were killed and the vascular structure was observed by scanning electron microscope and optical microscope,with the serum cholesterol level,superoxide dismutase(SOD) activity and malondialdehyde(MDA) level determined.Results Scanning electron microscopy showed that the endothelial cell lining in the iliac artery of the control and SND group remain regular,but the arteries in the model group presented with desquamated and exposure of the collagen fibril beneath the endothelium.Optical microscope revealed narrowed vascular lumen,thicken intima and numerous arteriosclerotic plaques in the model group in comparison with the control group,whereas the vascular lumen and intima thickness remained basically normal in SND group.The levels of total cholesterol,low-density lipoprotein cholesterol and triglyceride were decreased with high-density lipoprotein cholesterol levels increased in SND group,which was not observed in the model group.The serum SOD activity was higher in the control group than in the model and SND groups,but SND group had higher serum SOD activity than the model group.The serum MDA level was lower in the control group than in the other two groups,but SND group had lower MDA level than the model group.Conclusion SND can alleviate intimal hyperplasia and vascular stenosis in injured rabbit iliac artery,possibly in relation to increased SOD activity and decreased lipid peroxidation as a result of SND treatment.