This article reviews the percutaneous interventional procedures that can be used in the cardiac catheterization laboratory to treat or to palliate congenital cardiac lesions, both primarily or in conjunction with surgical repair. Many procedures, such as balloon atrial septostomy, balloon valvuloplasty for pulmonary and aortic valvar stenosis, and balloon angioplasty for pulmonary artery branch stenosis and recurrent coarctation, are routine in many laboratories. Standard radiologic techniques, such as coil embolization, are being used in the catheterization laboratory to occlude small to medium patent ductuses; unwanted systemic or venous collaterals; and less common lesions, such as coronary or pulmonary arterial fistulae. Finally, procedures such as stenting of pulmonary arterial stenoses and other postoperative narrowings and transcatheter closure of intracardiac defects are still being investigated and are very promising.