Although dystrophic aortic regurgitation is considered to be a rare condition, if aortic regurgitation due to cystic media-necrosis which usually presents with annulo-aortic ectasia and regurgitation due to dystrophic aortic valves are included, it becomes a relatively common cause of aortic regurgitation. In the authors' experience of 313 patients operated for pure chronic aortic regurgitation, approximately 30% had dystrophic lesions and this was the second most common cause of aortic regurgitation after acute rheumatic fever. The clinical presentation is variable: excluding annulo-aortic ectasia, the other features of dystrophic aortic regurgitation are less well known. Eighty-nine cases without aneurysm of the ascending thoracic aorta were recensed and analysed in a French Cooperative study. They were divided into two groups with respect to the diameter of the ascending aorta measured by echocardiography. The incidence of late postoperative complications of the ascending aorta was higher in patients with a dilated aorta. The diagnosis of dystrophic aortic regurgitation is easy in patients with an aneurysm of the ascending aorta: in other cases, transoesophageal echocardiography is very useful for evaluating the valvular lesions. Surgical treatment of pure dystrophic aortic regurgitation with an aneurysm of the ascending aorta is well established but the best management of aortic regurgitation associated with only mildly dilated aorta is debatable.