Deep venous thrombosis (DVT) is a common condition in which the clinical diagnosis is notoriously inaccurate. The diagnosis is usually made in the Radiology Department by either Doppler ultrasound or conventional venography. The high clinical suspicion for DVT and the availability of these imaging modalities places an ever increasing burden on radiology departments. Light reflection rheography (LRR) is a non-invasive technique for assessing venous disorders. It is easy and quick and can be performed at the bedside or in the Radiology Department. LRR was prospectively compared with conventional venography in 50 consecutive patients undergoing investigation for possible DVT. LRR was entirely normal in 24 patients and this was confirmed on venography in each case. In practice it was not always possible to differentiate between DVT and venous insufficiency in the 26 abnormal tracings but all 15 cases of venography-proven DVT were within this group. There were no false negative diagnoses of DVT. LRR is a simple and quick method of screening for DVT with significant cost saving implications. A normal tracing reliably excludes the diagnosis, whilst all abnormal tracings should undergo Doppler ultrasound or venography.