Eight infants with congenital cyanotic heart defects, aged 7 days to 10 months, weighing 2.9 to 10.0 kg, underwent percutaneous balloon pulmonary valvuloplasty as a palliative procedure to improve pulmonary oligemia. The indication for valvuloplasty was cyanotic heart defect not amenable to total surgical correction at the age and size at presentation but at the same time requiring palliation of pulmonary oligemia. After balloon valvuloplasty, there was an increase in the pulmonary blood flow index (1.83 +/- 0.55 to 3.14 +/- 1.38 L/min/m2; p less than 0.05), pulmonary-to-systemic flow ratio (0.55 +/- 0.35 to 1.19 +/- 0.63; p less than 0.05), and pulmonary artery pressure (15.5 +/- 6.6 to 29.1 +/- 12.1 mm Hg; p less than 0.02). Arterial oxygen saturation, although increased from 69.6 +/- 11.5% to 81.4 +/- 12.3%, did not attain statistical significance (p greater than 0.05). Immediate surgical intervention was avoided in all eight patients. At follow-up, 4 to 12 months after balloon valvuloplasty, all infants were thriving with decreased hypoxemia and polycythemia. Follow-up catheterization data were available from six patients, 3 to 10 months after valvuloplasty, and in all of them the immediate postballoon valvuloplasty improvement persisted or further improvement noted. These data suggest that pulmonary valvuloplasty offers excellent palliation of pulmonary oligemia in cyanotic heart defects, thus avoiding the risks of immediate surgical palliation and paving the way for a better result of eventual total surgical correction.