Computed tomography was employed in 37 patients suspected of having an aortic aneurysm: it was demonstrated in 32. Additional angiography was performed in 13, in eight of whom thoracic or thoracic-abdominal aneurysm was diagnosed, in five with dissection. Computed tomography gave a more exact measure of length and width of the aneurysm than angiography. The renal arteries were involved in four instances, pelvic arteries in seven. Both arteriography and computed tomography demonstrated dissection of the thoracic aneurysm.