Aim To explore the effects and its mechanisms of ginsenoside-Rg1 on level of t-PA and PAI-1.Methods Type 1 plasminogen activator inhibitor(PAI-1) and tissue type plasminogen activator(t-PA) activity in plasma were assayed using chromogenic substrate.Results The results showed that ginsenoside-Rg1 in vitro or in vivo significantly inhibited PAI-1activity,while increased t-PA activity.These effects were concentration-dependent.Intravenous Panax notoginsenoside Rg1 at 30,60,120 and 240 mg?kg~(-1) markedly suppressed PAI-1 level in plasma as well as platelet-released substances stimulated by thrombin,while increased plasma t-PA activity.And release level of PAI-1 owing to blood platelet was greatly decreased by ginsenoside-Rg1.Conclusion Ginsenoside-Rg1 showed potent antithrombosis due to the inhibition of PAI-1 and increase of t-PA.It might also be a advantagous mechanism to its antithrombsis.