Echocardiographic studies in patients with Marfan's syndrome indicate that 95% eventually have aortic root dilatation, mitral valve prolapse, or a combination of these. Both lesions can progress and require operation for aortic root aneurysm, aortic valve insufficiency, and mitral valve insufficiency. This report reviews the simplified treatment of 6 patients by combined composite valve graft replacement of the aortic root and transaortic mitral valve replacement at one operation. All patients survived and are well for periods extending from 1 month to 12 months.