OBJECTIVE Assessment of the results of percutaneous transluminal balloon pulmonary valvuloplasty (BPV) in children. METHODS Retrospective analysis of the methodology and results between October 1985 and October 1990. SITE OF THE STUDY: Pediatric Cardiology Service, Santa Marta Hospital, Lisbon. METHODS 43 consecutive children with pulmonary valve stenosis. 4 children with Noonan's Syndrome were excluded from the study and the results of 45 valvuloplasties in 39 patients are analysed. METHODS Full diagnostic catheterization and right ventricular cineangiography were performed. One or two balloon dilatation catheters were inserted percutaneously in one or both femoral veins and positioned across the pulmonary valve under fluoroscopic control. The balloons were then inflated to their maximum pressure with diluted contrast medium. In 18 children follow up cardiac catheterization was performed 3 to 12 months after valvuloplasty (mean 6.7 /+- 2.7). RESULTS A satisfactory dilatation was achieved in 35 patients (89%) with a substantial decrease in right ventricular systolic pressure (RVP) and in transvalvar peak systolic gradient (GR) (p less than 0.0001). A further significant spontaneous reduction in RVP and GR was recorded on follow up catheterization (p less than 0.01). A repeat BVP was performed in 6 children and was successful in 5. In cases a satisfactory relief of the stenosis was not achieved and 3 of them were submitted to surgery. There were no deaths. One child had cardiac arrest leading to successful surgical valvotomy and with no sequelae. Another child had cerebral embolism with hemiparesis. Ligation of a femoral vein was required in one case for haemorrhage. Mild pulmonary insufficiency resulted in 15 children. CONCLUSIONS Our experience confirms that BPV is the method of choice for the treatment of children with pulmonary valve stenosis either isolated or associated to small ventricular septal defect. It proved to be a safe and effective technique for reduction of GR. Mortality, morbidity, costs of the treatment and hospitalisation time are lower for BPV than for surgery with comparable short term results.