OBJECTIVE:To explore the blood circulation acti-vating effect and mechanism of Sanqi (Radix No-toginseng) in vivo,using a venous thromboembo-lism (VTE) rat model.METHODS:We established the VTE rat model,and then intervened with low molecular weight hepa-rin (LMWH),as well as low,medium and high doses of Sanqi (Radix Notoginseng),to observe the blood circulation activating effect of Sanqi (Radix Notogin-seng) on VTE rats.RESULTS:After the treatment with high concentra-tions of Sanqi (Radix Notoginseng),the pulmonary thromboembolism was alleviated,and the lower limb thrombosis was markedly improved.More-over,the expression quantities of plasma activated partial thromboplastin time,prothrombin time and D-dimer,as well as endothelin,von Willebrand fac-tor,and plasminogen activator inhibitor-1 in throm-bosis segment tissues were markedly down-regu-lated;while those of nitric oxide and tissue-type plasminogen activator were up-regulated.After low and medium concentration Sanqi (Radix No-toginseng) treatment,no obvious improvement was observed in each index.Moreover,the high concentration Sanqi (Radix Notoginseng)showed comparable efficacy to the positive drug LMWH.CONCLUSION:This data suggests that high con-centration of Sanqi (Radix Notoginseng) is effective in preventing and treating VTE.