Echographic examination for leg vein thromboembolism was carried out in 123 patients scheduled for thoracic surgery. Preventive measures for thromboembolism were conducted after the risk assessment. Echography was done after surgery in 72 cases, most of which were cases of lung malignant tumors, and thromboembolism was detected in 4 cases. Thus, the incidence rate of venous thromboembolism was 5.6%( 4/72). There was no patients who developed pulmonary thromboembolism during the examination period, suggesting reasonable risk assessment and preventive measures in our procedure.