Hemorheology including blood viscosity,visco-elasticity and thixotropy has been studied in 71 patients with deep vein thrombosis in lower extremity.All the cases were confirmed by phlebography.The results showed high blood viscosity,decreased in red blood cell elasticity and increase value on each point of thixotropy-Hysteresis Loop in all.As compared with the control group,there is significant difference(p<0.01).However,the area of the Hysteresis Loop and the energy consumption have no remarkable difference(p>0.05)between the two groups.It reveals that the blood viscosity,red blood cell visco-elasticity and thixotropy take part in the formation of thrombosis.