Aortopulmonary window is usually treated surgically. However, small windows far from the coronary and pulmonary
branch arteries can be occluded by transcatheter approache. The key step is the precise sizing of the defect. We report two successful transcatheter closures. We used CT angiography for precise measurement of the defect in the first patient, and balloon sizing in the other. We used duct occluders in both patients.