The irritable bowel syndrome(IBS) is the most common gastrointestinal disorder in clinical practice and is characterized by abdominal pain associated with a chronic disturbance of defecation. The subject is a-69-year-old man who has abdominal pain, chronic diarrhea. anorexia. general weakness and has been diagnosed as irritable bowel syndrome. We diagnosed this patient as the Gastrointestinal Phlegm(食痰) and prescribed Jengjengamiyijin-tang (Zhengchuanjiaweierchen-tang). In the result, we had improvement of his symptoms.