Coarctation and dystrophic aneurysm of the thoracic aorta are seldom associated. In this series of 6 patients the aneurysm, often voluminous, was located on the ascending aorta in 1 case, on the distal part of the aortic arch in 3 cases and on the descending aorta in 2 cases. Surgical treatment consisted of resection and prosthetic replacement of the coarcted and aneurysmal segment under extracorporeal circulation. In a 13-years old patient, however, the coarctation was repaired but the aneurysm of the descending aorta below it was deliberately left in situ. All six patients are now asymptomatic. Post-operative angiography was performed in 4 cases with satisfactory results. In all cases the dystrophic aneurysm resulted from lesions of the elastic fibers of the tunica media and was therefore different from other aneurysms associated with coarctations.