We describe a rare complication which occurred during catheter balloon valvuloplasty to the stenosis of the pulmonary artery. A 4-year-old girl with cyanosis who was diagnosed as having tetralogy of Fallot, patent foramen ovale and Down's syndrome underwent the cardiac catheralisation and angiography. Angiography showed the stenosis from outlet of right ventricle to bifurcation of the pulmonary artery. We attempted catheter balloon valvuloplasty to the stenosis of the pulmonary artery subsequently. We used the PTA catheter (NuMED INC, canada), 10 mm in diameter. The balloon was inflated twice (6 atm, 5 sec, 8 atm, 7 sec) at the bifurcation of the pulmonary artery safely. However, during third trial to inflate to 8 atm, it proved impossible to increase pressure to the desired level of 8 atm. Blood backed up in the catheter and it became impossible to deflate the balloon. We failed to remove the catheter through the left femoral vein, so we led the catheter to the right internal jugular vein with a guidewire. The catheter was successfully extracted in this way. The proximal connection between the balloon and the outer tube was broken and the balloon was compressed. To our knowledge, such as complication as this has not reported previously.