Chronic venous leg ulceration, which tends to recur, is difficult to treat and therefore needs special diagnostic and therapeutic care. We recently treated a 45-year-old patient with an obstruction of the left external iliac vein, caused by deep venous thrombosis. We would like to propose that, although rare, the existence of pelvic vein thrombosis and obstruction can cause venous leg ulcers. This case clearly pointed out that in patients with crural leg ulceration, showing no other signs of chronic venous insufficiency and where duplex ultrasound is normal, additional diagnostic evaluation should be performed. Because standard duplex ultrasound investigation can fail to demonstrate the obstruction, phlebography should be used in suspected cases as a secondary test to check both the superficial and the deep venous system for pathology, applying the endovascular therapeutic stent-placement technique.