The ascending leg venogram was performed in one hundred forty six lower extremities on the 7th day following total hip replacement or total knee replacement. RESULT : 1. Overall incidence of deep vein thrombosis in 146 limbs who underwent THR or TKR was 10% 2. The anatomic distribution of DVT: was as follows : In THR, 12.5% in FV, 25% in FV and PV and , 12.5% in FV and CV, and 25% in CV. in TKR, 100% in CV. 3. There were many anatomic variations i deep veins of lower extremities : Accessory SFV, double PV. 4. There were multiple SFV in 37%, and 19% of these limbs had DVT. It represented statistcally higher than 4% in limbs with a single SFV. 5. The incidence of DVT was 8% in cases of multiple PV, and there was no statistcally significant difference between these groups and single PV groups. 6. We could assess number of valves from popliteal vein to common femoral vein in 72 limbs. Mean number of valve was 5.45 and there was no statistically significant difference between broup having valve over 5 and under 5.