The association of hypoplastic left heart syndrome with pulmonary valvular abnormalities such as dysplasia, stenosis, or insufficiency is rare and not well defined in the literature. We report a rare case of hypoplastic left heart syndrome with a thickened four-leaflet, four-sinus pulmonary valve. After stage I palliation, this neo-aortic valve developed clinically significant insufficiency in the setting of increased pulmonary blood flow.