Even with highly developed ultrasound systems, diagnosis of deep leg vein thrombosis is difficult in lower leg veins and in the area of the adductor channel. In order to evaluate color duplex-sonography, contrast media duplex-sonography and phlebography in comparison, 79 patients (38 men and 40 women aged 54 to 89) with deep leg vein thrombosis were examined. As a result, patients suffering from thrombosis were characterized by a vein-artery quotient of > 2.0 (p < 0.01). In color Doppler duplex-sonography false negative findings occurred in 12 cases of lower leg vein thrombosis and in 3 cases of thrombosis within the adductor channel. By contrast media duplex-sonography the diagnostic reliability could be increased to a sensitivity of over 95 per cent.