Aim To investigate the expression of tissue factor(TF) and its mechanism in endothelial cell induced by fluid shear stress in vivo. Methods Fifty-four male SD rats(weight 300±16 g) were randomly divided into nine groups(n=6,respectively). The time course of mRNA and protein expression of TF,nuclear factor stimulatory protein(Sp1) and early growth response-1(Egr-1) were examined on the model of loop ligature method of stenosis the left arteries carotis communis intima in the rat with the combination of in situ hybridization and immunohistochemistry methods,performed computer image analysis were used. Results The mRNA and potein of TF and Egr-1 and Sp1 were faintly expressed in intima of control group,after exposed to stenosis,the staining intensity was increased 30 minutes after wall shear stress.The mRNA and protein expresion of TF markedly increased compared with control group(p<0.05).The mRNA and protein expresion of Egr-1 and Sp1 increased(p<0.05).The change of Egr-1 was more significant than that of Sp1(p<0.05).The change trend of Egr-1 and Sp1 expresion were similar to that of TF.The mRNA and potein of TF peaked at 6 hour,the mRNA and potein of Egr-1 peaked at 3 hour,the mRNA and potein of Sp1 peaked at 1 hour,with significant differences from control group(p<0.05). Conclusion In carotid artery stenosis, the shear stress can up-regulate TF expression in the endothelium,and its mechanism is related to the activation of Sp1 and Egr-1.