A 69-year-old man with an isolated right internal iliac artery aneurysm measuring 5.6 cm in diameter was treated with percutaneous embolization inducing thrombosis of the aneurysm. Four months later, he was seen with thrombosis of the right common iliac vein and pulmonary embolus. He subsequently underwent ligation of the aneurysm and repair of the right common iliac artery. Computed tomographic and operative findings suggested that the iliac vein thrombosis was the result of direct compression by the aneurysm itself, as well as perianeurysmal inflammation that encased the right common iliac vein. This report summarizes this case and presents a new potential long-term complication after successful selective embolization of an internal iliac artery aneurysm.