Two-dimensional echocardiographic studies were performed in 23 patients with coarctation of the aorta, 5 with interruption of the aortic arch, 6 with supravalvular aortic stenosis, 3 with truncus arteriosus, 2 with anomalous origin of the right pulmonary artery from the ascending aorta and 2 with aorto-pulmonary septal defect. The diagnosis was confirmed in each patient by surgery and/or cardiac catheterization and angiography. Visualization of the junction of isthmus and the descending aorta was possible in 18 of 23 patients with coarctation by two-dimensional echocardiography. In 13 patients correct diagnosis was obtained prospectively and in 2 patients coarctation was detected retrospectively. In only one of the 5 patients with interruption correct diagnosis was obtained and in 3 patients it was difficult to differentiate interruption from coarctation. In 5 of the 6 patients with supravalvular aortic stenosis, visualization of the area of obstruction was possible to two-dimensional echocardiography. In 2 of the 3 patients with truncus arteriosus, in whom none of the 2 had anomalous origin the right pulmonary artery from the ascending aorta and one of the 2 had aorto-pulmonary septal defect, correct diagnosis was obtained prospectively by two-dimensional echocardiography. Two-dimensional echocardiography may offer a useful noninvasive method for the direct visualization of aortic obstructive lesions and aortic malformations.