Objective : The purpose of this study is to compare anti-thrombotic activities of 4 Rhubarb species. Methods : Rhubarb has been used as medical and edible resources worldwide for the therapy of cancer, constipation and inflammation, etc. To compare the anti-thrombotic activities among the species within rhubarb, we investigated and compared the inhibitory properties of water extracts from R. palmatum(RPE), R. officinale(ROE), R. nobile(RNE), and R. franzenbachii (RFE) on the fibrinolysis, blood coagulation and platelet aggregation. APTT and PT, blood coagulation time, were measured by apparatus of auto blood coagulation analysis that called ACL-7000. The measurement of fibrinolysis was measured and compares with the width of clear zone from melted fibrin plate. The platelet aggregation was measured and compared with inhibition rate of aggregation. Results : We found out the best species from rhubarb showing the significant fibrinolytic, anti-coagulant and anti-platelet aggregation activity. Our results show that Rheum nobile (RNE) has the most effective anti-thrombotic activity among 4 tested rhubarb. Conclusions : This study, therefore, RNE will be able to be used the development of drug which is thrombosis treatment.