The conservative treatment of deep leg and pelvic vein thrombosis leads to permanent damage of recanalised veins, which in cases of long distance clots as well as involvement of the pelvic level, increase the risk of developing a postthrombotic syndrome. Such subsequent damage of the deep veins can only be avoided if occluded veins are rapidly recanalised and the function of the valves is successfully reestablished. Recanalisation may consist of surgical, fibrolytic and interventional methods and aims to minimize any subsequent damage; however no potential benefit of recanalisation versus standard treatment has yet been proven by means of methodologically adequate comparative studies. Thus, the indications for recanalisation must remain strict and be founded on a thorough risk-benefit assessment.