Motility and visceral hypersentitivity are regarded as the primary mechanisms of symptom development in irritable bowel syndrome(IBS). While a variety of motor abnormalities have been described throughout the gastrointestinal tract in IBS, their specificity and relationship to symptoms remain unclear. Visceral hypersensitivity is ubiquitous in functional gastrointestinal disease and is especially common in IBS. Again, however, its specificity for IBS has been questioned. Many factors, including stress and psychopathology,complicate the interpretation of these phenomena and new re-search suggests that mucosal inflammation and luminal factors may be more fundamental to the etiology of this common disorder.