We report the successful management of a 66-year-old man who had common iliac aneurysmosigmoid colon fistula. The initial presentation was abdominal pain, fever, and melena. Digital subtraction angiography showed no evidence of rupture. However, computed tomography scanning revealed fine gas formations in the common iliac artery aneurysm. To reduce the risk of graft infection and prolonged ischemia, we created an extraabdominal femoral-femoral bypass graft, closed the wounds, removed the aneurysm, and closed the colon primarily. The postoperative course and recovery were uneventful.