A 59-year-old man was admitted for dyspnea on exertion and edema. The patient did not have any pulmonary diseases that could cause dyspnea. Transesophageal echocardiography on the tilting bed with contrast infusion revealed a right-to-left shunt through the patent foramen ovale. Therefore, he was diagosed as platypnea-orthodeoxia syndrome due to the patent foramen ovale. Surgical closure was done and all of his symptoms had improved.