Platypnea-orthodeoxia is a rare condition characterized by dyspnea and oxygen desaturation induced by the upright position and relieved by recumbency. The most common cause of this syndrome is right-to-left shunt through interatrial communications such as patent foramen ovale (PFO) or atrial septal defect (ASD). In addition, this syndrome can be caused by other extracardiac components, including pulmonary emphysema, pericardial disease, and prominent Eustachian valve. We experienced 3 cases of this syndrome, including 1 patient with PFO and 2 patients with ASD. Computer tomography imaging revealed aortic elongation and compression of the right atrium by ascending aorta in all of 3 patients. Transcatheter closure of PFO or ASD was successfully performed in all patients, including immediate improvements of symptoms and oxygen saturation without any complications.