Roentgenographic studies, including plain chest roentgenography, thoracic aortography, and coronary angiography, were performed in seven adult patients with nonobstructive coarctation, a congenital deformity of the upper thoracic aorta. The chest roentgenographic findings were compared with those of ten patients with obstructive coarctation studied during the same period. A great similarity was found in the morphology and associated lesions of these two conditions, which supports the idea that nonobstructive and obstructive coarctation are stages of the same disease. Patients with nonobstructive coarctation had a more prominent aortic arch, and the indentation in the thoracic aorta was higher than in patients with obstructive coarctation. In addition, patients with nonobstructive coarctation had no rib notching on plain chest roentgenograms. Angiographic evaluation in patients with nonobstructive disease demonstrated the anatomic lesion, the absence of collateral circulation, and the commonly associated anomalies of the aortic valve.