Primary iliac venous aneurysm is an extremely rare vascular abnormality that is associated with the likelihood of rupture, embolism, and thrombosis. In this report, we describe the case of a ruptured aneurysm of the external iliac vein in a 63-year-old woman who was admitted to the emergency department and diagnosed by computed tomography. Computed tomography indicated a 4 × 5-cm ruptured aneurysm in the right external iliac vein that was surrounded by hematoma in the right side of the pelvis. The aneurysm was successfully treated by tangential aneurysmectomy and lateral venorrhaphy.