After emergency repair of a ruptured abdominal aortic aneurysm associated with an aortocaval fistula, Clostridium septicum sepsis prompted evaluation for colon cancer. Adenocarcinoma of the right colon ultimately required hemicolectomy, after which the patient had development of recurrent C. septicum bacteremia. Computed tomography scanning demonstrated a large fluid collection surrounding the aortic graft, and percutaneous drainage documented recurrent C. septicum. Initial axillobifemoral bypass was followed by removal of the patient's aortic graft and retroperitoneal drainage. After 3 years the patient is without evidence of recurrent infection or tumor. This case report consists of a known instance of C. septicum infection of an aortic graft.