The effectiveness of cutting balloon (CB) therapy was evaluated in severe pulmonary artery (PA) stenosis resistant to high-pressure balloon angioplasty in children with tetralogy of Fallot and pulmonary atresia. Thirty-eight pulmonary vessels (initial diameter 0.4 to 4.0 mm) resistant to high-pressure balloon angioplasty, as evidenced by a persistent waist, were treated with CB angioplasty in 12 patients. Thirty-two vessels underwent standard CB angioplasty and 6 vessels were treated with a CB catheter augmenting technique. Of the vessels treated with standard CB angioplasty, 17 vessels underwent subsequent high-pressure balloon angioplasty, 8 vessels had additional high-pressure balloon angioplasty and stent placement, and 7 vessels underwent CB dilation alone. The diameter of these vessels increased from 1.3 ± 0.7 to 2.8 ± 0.9 mm (p <0.001). Six of the 38 vessels were treated with a CB catheter augmenting technique; these vessels were larger with an initial diameter of 2.6 ± 0.8 mm and increased to 4.4 ± 1.7 mm (p <0.001). Of the 38 vessels, 35 increased by >50%, for a procedural success rate of 92%. Intimal damage was angiographically evident in 17 of 38 vessels (45%) after CB angioplasty; 1 procedure was complicated by an unconfined tear requiring coil occlusion of the distal vessel and another resulted in a confined tear, successfully managed with stent implantation. This study supports prior reports of successful angioplasty with CB therapy for resistant PA stenosis, identifies potential complications, and expands the experience to infants, larger vessels, and sublobar locations.