Sensorimotor disturbances of the small bowel are implicated increasingly in the pathogenesis of the functional gastrointestinal disorders. In irritable bowel syndrome (IBS), alterations in both interdigestive and postprandial motility have been described, for example, the specific peristaltic contractions that are normally present in the ileum appear to occur more frequently and to be associated with abdominal pain in some patients. The latter finding is likely to be related to the selective mechanoreceptor hypersensitivity that has been demonstrated in the small bowel of IBS patients. The level of this afferent dysfunction has, however, not been established; some evidence suggests that personality traits, which predispose to a more severe and prolonged sympathetic response to stressors, may hasten the development of such sensorimotor disturbances.