Balloon pulmonary valvuloplasty (BPVP) is the procedure of choice for the treatment of isolated pulmonary valve stenosis. Complications and failure of the procedure are more common in newborns and infants. Aim: To establish the effectiveness and safety of BPVP in newborns and infants. Material and methods: Ninety-one infants (11 newborns) with isolated pulmonary valve stenosis and mean age 171 ± 115 days were catheterized for BPVP between October 1986 and December 2016. BPVP was performed in 86 infants with a balloon catheter size 127±16% from the annulus dimension. The effectiveness (gradient right ventricle (RV) – pulmonary artery (PA) ≤ 35 mm Hg) and safety (lack of life–threatening complications, emergency surgery or death) of the procedure were assessed. Results: Transvalvular pressure gradient decreased from 82 ± 29 mm Hg to 29 ± 24 mm Hg (р = 0,0001) and RV pressure - from 101 ± 28 mm Hg to 52 ± 24 mm Hg (p = 0,0001). BPVP was effective in 61 infants (70,9%), mainly in those with lower initial gradient, RV pressure and less signifi cant infundibular obstruction. There were no children with hemodynamically signifi cant postprocedural pulmonary insuffi ciency. Complications were observed in 16 of the infants catheterized for BPVP (17,6%). In 5 of the children (5,5%), minor (transient) complications arose and were overcome by conservative means. Major complications were observed in 11 infants (12,1%): rhythm and conductive disorders (critical bradycardia, supraventricular/ventricular tachycardia, complete atrioventricular block) in 6 children, hemopericardium or severe right ventricular outfl ow tract rupture – in 5. The evolution was favorable after intensive treatment in 6 children with major complications, two children were sent for emergency surgery (2,2%) and death occurred in 3 of the children associated with the procedure (3,3%). The procedure was interrupted and BPVP was not performed in fi ve of the catheterized children (5,5%), all with severely dysplastic valve. Conclusion: BPVP is effective and comparatively safe procedure under the age of 1 year. Newborns, children with severely dysplastic valve and suprasystemic RV pressure are the most at-risk.