A 39-year-old woman with familial homozygous hypercholesterolemia had supravalvular and valvular aortic stenosis. Modified Nick's procedure and aortic valve replacement was performed to relieve both the supravalvular and annular stenoses. At surgery, the ascending aorta was found to be narrowing at the level of the sinotubular junction, which was compatible with congenital supravalvular aortic stenosis. Histological examination of the aortic cusps showed sclerotic change due to hypercholesterolemia. These findings indicated that familial homozygous hypercholesterolemia caused valvular aortic stenosis and exacerbated congenital supravalvular aortic stenosis.