Sixty-six patients with possible abnormalities of the thoracic aorta were examined by CT and the data compared with standard chest radiographs, angiography and, in most, with the surgical findings. Using contrast enhancement computed tomography was able to evaluate and differentiate between a tortuous aorta, an atherosclerotic aneurysm, and aortic dissection and extra-aortic masses. Distinguishing pathological features are discussed. In aortic dissections angiography may be necessary to delineate the site of the intimal tear. Long term follow-up of aortic dissections, especially Type III, is best done by CT. Aneurysmal rupture or leakage, as well as extension into the abdominal aorta, can easily be ascertained by this method.