Deep vein thrombosis is a frequently lethal complication following musculoskeletal surgery and skeletal trauma. For this study on incidence of deep vein thrombosis, we examined the data on 40 patients with contrast venography. Thrombosis limited to the veins in the calf of the leg was shown in 10 patients by venography. None of these patients had clinical symptoms of deep vein thrombosis or indicating embolism. We therefore concluded that the incidence of deep vein thrombosis of the lower extremity after injury or operation in Korea is not so rare as was considered before.