The causes of sciatica are variable and include musculoskeletal, dermatologic, infectious, neoplastic, and vascular disorders. In many cases, the symptom is usually caused by degenerative disease in the spine with the compression or irritation of spinal nerve. On the other hands, there are also several announced extra-spinal causes including aneurysm, diabetes, and radiation for sciatica in a low rate. Among the extra-spinal cases, aneurysms arising from iliac vessels are sometimes developing a diagnostic confusion with the spinal causes, and delayed diagnosis can lead to poor prognosis. It is very important to pay attention weather the aneurysmal cause is involved in the symptom of sciatica.