We examined the number of elastic lamellae in the wall of the proximal aortic arch, aortic isthmus and descending aorta in patients with coarctation of the aorta. In the proximal aortic arch, the number of elastic lamellae was significantly lower in patients with coarctation compared to those with normal hearts without aortic anomalies and those with intracardiac defects but without aortic anomalies. The isthmus also showed a significantly lower number of elastic lamellae in the presence of preductal coarctation. In the descending aorta, the number of elastic lamellae was not significantly different between the different groups. There is doubt about the etiology of coarctation. Recent investigations showed that cells from the cardiac neural crest contribute to the formation of the arch arteries and the media of the arch. A developmental error of the neural crest might be responsible for the abnormal mural structures found in patients with aortic coarctation.