A 31-year-old man has visited our hospital, complaining diarrhea and leg edema. Blood test showed hypoalbuminea, but we couldn't find the reason by several examinations. Therefore, we performed double balloon enteroscopy, and intestinal lymphangiectasia was diagnosed histologically by biopsy. It's useful and effective to perform double balloon enteroscopy and histological examination for the unknown origin case of protein loosing enteropathy.