Aim To transfect the endothelial nitric oxide synthase(eNOS) gene into the rats' common carotid arteries injured by catheter, then to observe the influence of the transfection on the stenosis degree of the vessles. Methods 55 male Wastar rats of 3 months age were divided into normal control group (n=10), blank control group (n=15), pcDNA3.1(-) transfection group (n=15) and eNOS trnsfection group (n=15). 45 rats were accepted the intimal catheter surgery of the left common carotid except the normal control group. After operation, pcDNA3.1(-) and pcDNA3.1-eNOS were transfected respectively into pcDNA3.1(-) and eNOS transfection groups by carrier of FuGENE 6. The rats were executed 2 weeks, 1 and 2 month after the operation, the transfected common carotid arteries were took out and stenosis degree of the arteries were measured. Results The eNOS mRNA could be detected in cultured smooth muscle cell and the stenosis degree was significantly decreased in eNOS transfection group (p<0.01). Conclusions eNOS gene could be transfected in vivo into the smooth muscle cell succesefully and the transfecton also could obviously decrease the stenosis degree of the catheter injuried arteries.