Twenty acute spinal cord injury patients were surveyed for deep venous thrombosis (DVT) by 125I fibrinogen leg scanning, impedance plethysmography (IPG), and venography. Leg scanning was a more sensitive indicator of thrombotic events than IPG or venography. IPG was a reliable indicator of accumulated thrombosis. The incidence of dvt assessed by leg scanning alone was 100 per cent. Its occurrence as determined by either of the screening techniques was found to be considerably greater than those of previous reports.