Pseudoaneurysms of the lower limb are rare and frequently iatrogenics ă complications. Closed traumas are likely to generate lesions of the ă arterial wall, which generally become symptomatic at a later stage. The ă diagnosis of such vascular lesion is difficult because the ă symptomatology and the onset can be delayed. We herein report the case ă of a 15-year-old patient in whom the diagnosis of pseudoaneurysm of the ă anterior tibial artery was made 5 months after a non-displaced closed ă fracture of the tibial shaft. The radiographs were evocative of a ă malignant bone tumor. The study of vessels by a contrast-enhanced ă CT-scan enabled us to diagnose the pseudoaneurysm. Before the occurrence ă of late onset swelling, a history of trauma must be sought, even old.