The simultaneous existence of thoracic aortic aneurysm and lung cancer is a rare finding, especially if the malignancy is primary and does not involve the aortic wall. In this report, we present a case of a typical descending thoracic aneurysm combined with a primary adenocarcinoma of the left lower lobe. The aneurysm was repaired with a Dacron graft without use of extra corporeal circulation and a typical left lower lobectomy was performed. In such cases, aneurysms should be treated primarily with endovascular stents. However, if this is not possible, a combined operation can be performed with good outcome.