In a combined retrospective and prospective study, 11 patients with adult polycystic kidney disease were found to have one or more cardiac or aortic lesions. Seven patients had primary dilatation of the aortic root and annulus with aortic regurgitation. The severity of the aortic regurgitation necessitated aortic valve replacement in 2. Mitral regurgitation was present in 3 patients, of whom 2 had documented redundant mitral leaflets and ruptured chordae tendinae, and the third had mitral valve prolapse. Histologic analysis of available aortic and mitral valve tissue from these acquired lesions showed myxomatous degeneration with loss and disruption of collagen. Four patients had congenital bicuspid aortic valves with aortic regurgitation; 1 of these patients also had mild valvular stenosis, and 1 had coarctation of the aorta.