In order investigate the effect of Boyanghwanotang (BT) on thrombosis, Sprague-Dawley rats injected endotoxin into the caudal vein were oral administrated solid extract of BT-182. 4mg/200g (Sample A) and 364.8mg/200g (Sample B), and then observed Platelet, fibrinogen, prothrombin time and FDP. Another group injected hydrocortisone acetate into the muscular rump were adopted to observe the effect of BT on elevated blood Viscosity, administrated Sample A and Sample B, thereafter measured body weight, body temperature, whole blood viscosity, plasma viscosity, hematocrit, RBC, WBC, hemoglobin, glucose, albumin, total protein, triglyceride, cholesterol and prothrombin time. 1. Platelet was increased significantly in Sample B compared with the control group. 2. Fibrinogen of the trial groups compared with the control group was increased, and revealed a significance in Sample B. 3. Prothrombin time was decreased significantly in the trial groups compared with the control group. 4. FDP was decreased in the trial groups compared with the control group. 5. Body weight was increased significantly in Sample B after 7 days, body temperature revealed a significance in the trial groups after 5 days. 6. Whole blood viscosity and plasma viscosity of lower shear rates, both were highly decreased in the trial groupn than the control group. 7. The increase of WBC and decrease of hematocrit, RBC and hemoglobin was showed in the trial groups, and Sample B revealed a significance on the increase of WBC and decrease of RBC. 8. The increase of prothrombin time and decrease of glucose, albumin, total protein, triglyceride and cholesterol was showed in the trial group, and Sample B revealed a Significance on the increase of prothrombin time and decrease of albumin, total protein and triglyceride. 9. As compare with Sample A and Sample B, generally Sample B was highly Significant. According to the above results, it was considered that Boyanghwanotang may be the curative effects for thrombosis and elevated blood viscosity.