The echocardiographic manifestations of segmental supravalvular aortic stenosis are described in 2 patients. The diagnosis was confirmed by cardiac catheterization in both and at operation in 1. A systematic echocardiographic approach to such patients is described. The characteristic finding in these patients was the narrowing of the diameter of the aortic lumen at the stenotic area just distal to the aortic valve. As the transducer sweeps further cephalad the aortic lumen widens to a normal diameter. In one patient treated surgically, postoperative echogram demonstrated the narrowing to be reduced.