One-hundred patients with pulmonary valve stenosis underwent pulmonary valvoplasty, their ages ranging from 1 to 59 years. The systolic gradient across the valve ranged from 47 to 260 mm Hg (97.67 +/- 41.15) prior to the valvoplasty, and from 0 to 55 mm Hg (14.72 +/- 11.40) immediately after dilatation (P less than 0.0001). The clinical follow-up of 18.2 months of 56 patients showed a tendency for the systolic thrill to disappear, the systolic murmur became softer and there was a tendency to normalization of the electrocardiogram. A hemodynamic restudy was carried out in 54 patients and the systolic gradients across the valve ranged from 21.55 +/- 23.86. Seven patients required redilatation. In patients with hypertrophy of the infundibulum prior to valvoplasty this was observed to regress, indicating that infundibular hypertrophy is reversible.