In order to investigate the effect of the Herba Segesbeckiae on the thrombosis induced by endotoxin in rats. The rats were treated with solid extract of Herba Siegesbeckiae 41.9mg /200g(Sample) which were administered orally. And the thrombosis was induced by injecting endotoxin in the caudal vein rats. And then the number of platelets, concentration of fibrinogen, prothrombin time and FDP(fibrinogen degradation product) were measured. The results were as follows; 1. Platelet was increased significantly in sample group compared with control group. 2. Prothrombin time was shortened significantly in sample group compared with control group. 3. Fibrinogen was increased significantly in sample group compared with control group. 4. FDP was decreased significantly in sample group compared with control group. According to the above results, Herba Siegesbeckiae had significant effects on number of Platelets, Prothrombin time, Fibrinogen and FDP. therefore, it is considered that Herba Siegesbeckiae can be applied to diseases related to thrombosis.