In a recently observed case of dissecting aneurysm there were present during life the typical signs of aortic insufficiency; at necropsy the aortic valves were found to be normal. Similar cases have been described by Börger,1Busse,2and Letulle.3In a few of the cases of dissecting aneurysm collected by Moreau4there were observed signs which may have been interpreted as being due to aortic insufficiency; but the anatomic findings are too inadequately detailed to allow one to judge of the condition of the aortic valves. We have not attempted to investigate the entire literature of dissecting aneurysm, which now comprises the reports of about 300 cases. It should be pointed out that in most instances death occurs so soon after the development of the lesion, usually as the result of perforation into the pericardium or pleural cavities, that satisfactory clinical observations have not been possible.