Fifty-six percutaneous transluminal balloon valvuloplasty procedures were performed in 51 patients suffering from congenital pulmonary valve stenosis. The patients ranged in age from 1 day to 60 years (mean 6.9 years); 21 were infants less than 1 year of age, including 8 neonates. The peak systolic pressure gradient was greater than 50 mm Hg (mean 81.5) in 47 cases, and less than 50 mm Hg (mean 34.6) in 9. Valvuloplasty enabled a reduction in the mean right ventricular peak systolic pressure from 93.1 to 51.6 mm Hg (p less than 0.001), the mean transvalvular gradient from 73.4 to 27.0 mm Hg (p less than 0.001) and the mean right ventricular pressure expressed as a percent of systemic pressure from 99.5 to 52.0% (p less than 0.001). In infants and neonates, the mean right ventricular pressure expressed as a percent of systemic pressure decreased from 117.3 to 64.4% (p less than 0.001). In 23 patients, follow-up cardiac catheterization at 1 to 17 months revealed a significant change in the right ventricular systolic pressure, which decreased from 54.0 to 46.7 mm Hg (p less than 0.05), and in the peak systolic pressure gradient, which decreased from 27.3 to 22.6 mm Hg (p less than 0.05). Valvuloplasty is an effective procedure in relieving pulmonary stenosis in patients of all ages, including neonates.