Abstract: The effect of sanchinoside Rg₁ on generation of thrombosis and its mechanism was studied. Rg₁ was shown to markedly inhibit experimental thrombosis formation induced by extra corporeal shunt between the carotid artery and jugular vein. After Rg₁ infusion, the activity of t-PA was found to be increased, so did the percentage of active-type t-PA, but the activity of PA-I decreased.Further data in our study indicate that incubation of endothelial cells with Rg₁ for 24 h caused significant increase of NO production. This effect was found to be dose-dependent.These observations suggest that Rg₁ is a potent anti-thrombosis substance and can enhance the function of fibrinolysis system and stimulate vascular endothelial cells to release NO.