Post-surgical stenoses in patients operated upon for tetralogy of Fallot create difficult therapeutic problems. Between November 1985 and November 1988, we performed 17 percutaneous transluminal angioplasties in 13 children aged from 5 to 15.1 years (7.7 years) for stenosis of pulmonary artery branches after correction of tetralogy of Fallot. Group I consisted of stenoses consecutive to palliative anastomoses: 6 dilatations of 5 stenoses in 4 children. Group II concerned stenoses of the pulmonary artery at the top of widening patch on the pulmonary trunk of bifurcation: 5 dilatations of 5 stenoses in 4 children. Group III was made of congenital stenoses sometimes located upstream of a widening patch which made them worse: 6 dilatations of 6 stenoses in 5 children. Angioplasty was performed after catheterization and angiocardiography, the diameter of the balloon being 1.2 to 4-fold that of the stenosis (mean 2.65). There was no complication. In 7 cases the diameter of the stenosis increased by 27 to 96 p. 100. In 2 of these cases, this increase produced no change in pulmonary pressures and perfusion. In the remaining 5 cases, regarded as successful, the diameter of the stenosis increased from 5.7 mm to 9 mm on average, and the right ventricular pressure fell from 62.4 mmHg to 48.8 mmHg; the gradient was reduced by 24 to 50 p. 100 in 4 cases and the lung perfusion was improved in the 5th case. The proportions of successful angioplasties were: 2 out of 6 in group I, zero out of 5 in group II and 3 out of 6 in group III.(ABSTRACT TRUNCATED AT 250 WORDS)