In children with a univentricular heart and a rudimentary subaortic chamber, surgical relief of subaortic obstruction caused by a restrictive bulboventricular foramen is associated with high morbidity and mortality. A 6-year-old child with a univentricular heart of the left ventricular type, a rudimentary subaortic chamber, and atresia of the left-sided atrioventricular valve had pulmonary artery banding in infancy. Severe subaortic obstruction subsequently developed. At operation, the pulmonary artery was transected and the stump was anastomosed directly to the posterior aspect of the ascending aorta, diverting left ventricular blood into the aorta through the pulmonary valve. The distal pulmonary artery was anastomosed side-to-side to the ascending aorta to provide pulmonary blood flow. Cardiac catheterization fifteen months after the operation demonstrated an excellent hemodynamic result. When the pulmonary artery is adequate in size, a bypass operation by way of an anastomosis between the ascending aorta and the pulmonary artery is a relatively safe and effective means of relieving the ventricular outflow obstruction caused by a restrictive bulboventricular foramen.