A 72-year-old woman underwent simultaneous combined surgical treatment for descending aortic aneurysm, coronary artery disease and left common iliac artery stenoses. The operation was performed through the left posterolateral thoracotomy via the 6th intercostal space and a left retroperitoneal approach. At first, 10mm woven Dacron graft was anastomosed to the abdominal aorta as an inlet of the cardiopulmonary bypass and the left femoral vein was used for venous drainage. A saphenous vein graft was anastomosed to the left anterior descending artery during partial cardiopulmonary bypass with the heart beating. Secondly, the aneurysm was replaced with 24mm woven Dacron graft. Thirdly, the proximal end of the vein graft was anastomosed to the Dacron graft of the descending aorta. Finally after cardiopulmonary bypass was terminated, the distal end of the woven Dacron graft for arterial perfusion was anastomosed to the left external iliac artery in end-to-side fashion. The postoperative course was uneventful. We conclude that simultaneous operation for descending aortic aneurysm and coronary artery bypass grafting through left thoracotomy with the heart beating is useful in these combined diseases.