Supravavular aortic stenosis is a congenital narrowing of the ascending aorta just distal to the level of the origins of the coronary arteries, that may be localized or diffuse. Five patients with supravalvular aortic stenosis were operated upon between July, 1986 arid June, 1990. Four of these patients were William`s syndrome [mental retardation, elfin face], and one was isolated supravalvular aortic stenosis. Preoperative diagnosis of the supravalvular aortic stenosis was made by left side cardiac catheterization and angiocardiography. There are three types of supravalvular aortic stenosis such as membranous, hourglass and hypoplastic. Four of our patients were of hourglass type, and one was hypoplastic type. Patch aortoplasty was performed in all cases. Preoperative systolic gradients ranged from 45 to 1SO mmHg [average 102.6 mmHg]: postoperative gradients ranged from 0 to 75 mmHg [average 39 mmHg]. The patient of hypoplastic type has been suffered from mild exercise intolerance even after the operation, and the postoperative echocardiography revealed the systolic gradient of 100 mmHg [preoperative 180 mmHg]. The results of surgery for hourglass type were excellent. But the patient with hypoplastic form would be benefited from some modifications of the operation.