Thrombosis of the veins of the lower limbs and of the inferior vena cava can be diagnosed by free flow phlebography completed by a technical device preventing puncture of the femoral veins. The thrombus shows as a lacuna or a cupshaped arrest of the contrast medium. This method can be used in most modern radiological centres and carries little risk in trained hands. Its field of application is limited in that the pelvic veins (iliac veins excepted) and the deep femoral vein are imperfectly explored or unexplored, but it is superior to other methods - such as labelled fibrinogen, Döppler ultrasonography or rheography - which are less sensitive, less specific and unable to localize precisely the site and extension of the thrombosis. However, these methods can be used at the patient's bedside and can be repeated at will, being painless. Whenever pulmonary thrombo-embolism is suspected on clinical grounds or on the results of other exploratory methods, phlebography should be systematically performed (except in pregnant women) as it helps to decide on the treatment. In contrast, it has no place in the routine detection and surveillance of the disease which are better carried out using non-invasive techniques.