Objectives: We evaluated the efficacy of percutaneous transluminal coronary angioplasty for anastomotic stenosis after coronary arterial bypass grafting using the internal thoracic artery in patients with coronary arterial lesions due to Kawasaki disease. Subjects and Methods: From July 1997 to April 2000, four boys and one girl underwent percutaneous transluminal coronary angioplasty for 6 anastomotic lesions following coronary arterial bypass grafting using the left or right internal thoracic artery. Progressive severe stenosis of the grafts in the follow-up angiograms after grafting, and evidence of ischemia, were regarded as indications for percutaneous transluminal coronary angioplasty. Age at coronary angioplasty ranged from 4.2 to 16.7 years, with a median of 6.9 years, while the interval from operation ranged from 0.3 to 3.0 years, with a median of 1.1 years. The diameter of the balloon catheter employed varied from 1.5 to 2.5 mm, and the pressure of inflation ranged from 8 to 16 atmospheres. Results: The degree of stenosis decreased from 63 to 99%, with a median of 88%, to 0 to 40%, with a median of 17% immediately after angioplasty. A follow-up angiogram either 3 months or 1 year later revealed no restenosis in any patient. Conclusion: Percutaneous transluminal coronary angioplasty is a feasible and useful procedure for treating anastomotic stenosis following coronary arterial bypass grafting using the internal thoracic artery in patients with coronary arterial lesions due to Kawasaki disease.