A female infant with unilateral pulmonary agenesis developed congestive heart failure dominated by symptoms of obstructive disease of the airways at 3 1/2 months of age. Cardiac catheterization revealed total anomalous pulmonary venous connection to the right atrium. Despite a massive left-to-right shunt with one pulmonary artery receiving the entire right ventricular output since birth, the patient's resting pulmonary vascular resistance was normal. Open heart surgery to repair the cardiac lesion was performed when the infant was four months of age. Subsequent studies revealed an excellent anatomic and functional repair, with normal pulmonary arterial pressures. One year following surgery, the child is asymptomatic and has normal growth and development.