Eosinophilic gastroenteritis is rare disease characterized by peripheral eosinophilia, eosinophilic infi ltration of the gastrointestinal tract and functional gastrointestinal abnormalities. Common symptoms are abdominal pain, nausea, vomiting, diarrhea (bloody or non-bloody), weight loss, and ascites. A 59-year-old man was admitted to this hospital with a chief complaint of dyspnea that developed fi ve years ago. His dyspnea corresponded to the NYHA grade II on admission. He had no other history of illness except for hypertension, and he never smoked. The initial laboratory data showed thatWBC 5520/㎕(with 50.1% neutrophil, 38.2% lymphocyte, 6.8% monocyte, 4.5% eosinophil and 0.4% basophil); sodium, 139mmol/L; potassium, 4.4mmol/ L; chloride, 105mmol/L and proBNP, <8 pg/mL. The ECG showed normal sinus rhythm. The chest radiograph was within normal limits. Pulmonary function test showed FEV1, 101% of predicted while FVC 127% of predicted. The metacholine provocation test was negative. He had uncontrolled watery diarrhea fi ve times a day and tenesmus for the last fi fteen years. He was treated with a suspicion of having irritable bowel syndrome and functional diarrhea, but his symptoms did not improve for the last fi fteen years.In an attempt to investigate the pathophysiology of diarrhea, gastrointestinal endoscopy and histology were performed with a subsequent diagnosis of eosinophilic gastroenteritis. Methylprednisolone was administered for a total of ten days. He was discharged from hospital with montelukast, levocetirizine and hydroxyzine maintained. This patient had neither recurrent diarrhea nor tenesmus. As eosinophilic gastroenteritis presenting as dyspnea in adults has not been previously reported in the literature, we thought this could guide diagnosis in future cases.