High-pressure, high-resistance ventricular septal defects were closed in 55 patients. Pulmonary arterial bands had been placed in infancy in 20. For the 55 patients, the hospital mortality was 7.2%, 5.6% in patients with primary closure of VSD and 10% in patients with additional banding procedures. In two patients, operative mortality was directly related to significant associated congenital intracardiac lesions. In 22 patients catheterized 1 yr following primary closure of ventricular septal defects, PVR decreased from an average of 1475 to 480 dynes/sec/cm-5. In six of eight patients operated upon within the first 4 yr of life, total PVR decreased to normal levels. Pulmonary artery mean pressure decreased in the total group from 74 mm Hg preoperatively to 31 mm Hg postoperatively. In patients with previous pulmonary arterial banding, mean PVR decreased from 1920 to 700 dynes/sec/cm-5 following banding. PVR decreased further to 470 dynes/sec/cm-5 following closure of the ventricular septal defect and removal of the pulmonary artery band. Because of the presence of residual outflow gradients found at either the band site, pulmonary valve, or right ventricular infundibulum, the results of the two-stage approach are considered suboptimal. We advocate primary closure of ventricular septal defects in symptomatic infants and elective closure within the first 3 yr of life in patients with large defects.