['To study disturbances of gastrointestinal motility and afferent (sensory) dysfunction in functional (unexplained) dyspepsia, and the interrelationships between motility and sensory dysfunction.', 'Twelve patients with functional dyspepsia and 12 controls matched for age and gender were studied. Intestinal perception thresholds were tested by a standardized stepwise distension procedure in the third portion of the duodenum with a barostat device. Small intestinal motility was measured with a low compliance perfusion system proximal and distal to the distending balloon.', 'First perception of duodenal balloon distension occurred at significantly (p <0.01) lower pressures in patients (23 +/- 3 mm Hg, mean +/- SEM) than in healthy controls (31 +/- 3 mm Hg). Patients had a lower maximal intestinal pain tolerance than controls (31 +/- 2 mm Hg vs. 39 +/- 1 mm Hg, p <0.05). Duodenal distension inhibited intestinal motility distal to the distending balloon (peristaltic reflex) more often in health controls (11/12) than in patients with functional dyspepsia (5/12, p <0.05). These alterations of small intestinal motility occurred at pressure values below the perception thresholds, and disturbed motility responses were not associated with perception thresholds.'] Are impaired small intestinal peristaltic reflexes and sensory thresholds independent functional disturbances in patients with chronic unexplained dyspepsia?