Four patients are described in whom combined aortic stenosis and regurgitation was evident on examination. In each of them obstruction to left ventricular outflow was shown to be due to congenital subaortic stenosis, and aortic regurgitation resulted from the sequelae of bacterial endocarditis. The presence of this unusual combination of congenital and acquired malformations was suggested by certain clinical findings, and results of the preoperative hemodynamic and angiographic studies that established the diagnosis are presented.In three patients the subaortic membrane was resected, and aortic regurgitation was corrected by reconstruction or replacement of the aortic valve. All of the patients evidenced striking clinical improvement after operation, confirmed by the results of postoperative hemodynamic assessments. A fourth patient died before operation; the pathologic findings are presented in detail.