Follow-up cardiac catheterization studies were used to evaluate 105 patients who had undergone percutaneous balloon pulmonary valvuloplasty. Fifteen of those patients who had peak systolic pulmonary valve gradients greater than = 40 mm Hg at follow-up underwent repeat balloon valvuloplasty. For the initial balloon pulmonary valvuloplasty, the mean ratio of the balloon diameter to pulmonary valve annulus diameter was 0.98 +/- 0.2; at repeat valvuloplasty the mean was 1.19 +/- 0.12. The immediate post-repeat balloon valvuloplasty results showed a reduction in the peak systolic gradient from a mean of 70.2 +/- 17.8 to 29.1 +/- 19.0 mm Hg (p less than 0.001). This reduction in the gradient was maintained at a mean of 14.3 +/- 5.0 mm Hg in 8 of the 10 patients who underwent further follow-up studies. We conclude that successful repeat balloon pulmonary valvuloplasty with the use of larger sized balloons is feasible in patients who have restenosis after the initial percutaneous balloon valvuloplasty--including partial but not complete dysplasia of the pulmonary valve.