THIS YEAR over 50,000 persons in the United States will die as a result of automobile accidents. Autopsy examination shows that 1 in 6 sustain fracture of the thoracic aorta (4). Immediate exsanguination occurs in most, but 10 to 20 per cent of the injured will survive long enough for reparative surgery provided the diagnosis is established (8, 12, 16). Correlation of radiologic with clinical evidence allows the diagnosis to be made with confidence. I t is our purpose to review the findings in 12 cases of aortic fracture, 10 of which were seen in the acute phase. Pathogenesis Nonpenetrating injuries of the thoracic aorta may be produced by direct forces such as compression or blast or by indirect forces such as deceleration, or by a combination of these. The forces generated by rapid deceleration in either the vertical or horizontal plane are the most common causes of aortic fracture (8, 12, 16). Haas (5) studied patients who died in airplane accidents and showed that vertical forces of deceleration produ...