Functional gastrointestinal disorders (FGID) such as functional dyspepsia (FD) and irritable bowel syndrome are common gastrointestinal diseases in clinical practice. FGID is not life-threatened disease, but it is an important disease because the patients with FGID have a poor QOL. Recently the Rome criteria for the diagnosis of FGID has been established in Western countries, however, whether the criteria is suitable for clinical practice in Japan or not has not fully discussed. Many factors including gastrointestinal dysmotility, abnormality of acid secretion, visceral hypersensitivity, Helicobacter pylori infection or stress might play in the pathogenesis of FD. Our previous studies using ultrasonography indicate the decrease in gastric emptying and antral motility and the increase in duodenogastric reflux in patients with FD. In the treatment of FD, prokinetic agents, acid-suppressive drugs and antidepressants have been widely used.