B-mode-compression sonography is the method of choice in detection of deep venous thrombosis of the lower extremity after surgery or immobilisation: It is readily available, repeatable at any time, and is the least stressing for the patient. Color-coded duplex compliments b-mode compression in selected cases, and is method of choice in follow-up exams to evaluate recanalisation. I.v.-phlebography has lost its importance and is only indicated in rare situations. Other picture-rendering methods couldn't be shown to be superior and hence did not find their way to clinical routine.