A pseudoaneurysm is a contained arterial disruption in the intimal and medial layers of an arterial wall. It may originate from a perforation caused by traumatic or iatrogenic injury or the dehiscence of a surgical anastomosis. Because of its insidious onset and delayed presentation, orthopaedic surgeons should be aware of the possibility of such a lesion after an initial trauma. We report on a case of a delayed huge pseudoaneurysm of the popliteal artery that occurred 11 months after conservative treatment of a supracondylar fracture of the femur in order to keep in mind the possibility of the delayed presentation of vascular injury after a distal femur fracture.