The term of Cockett's syndrome stands for a lower limb dysfunction with venous stasis originating from the left common iliac compression by the right common iliac artery at the pelvis inlet level. For the authors, there are three evolutive stages. First stage: a simple compression without any anatomic venous parietal lesion. Second stage: to the previous, are added left common iliac vein lesions consisting of an inner vascular band formation. This must be surgically treated to remove the obstacle. Third stage: the final evolution: the ilio-femorale thrombosis. Therefore, the diagnosis must be done as early as possible. It lies on the left lower limb phlebography.