Using a gastric barostat we have studied interdigestive variations in gastric tone and its response to gastric distention in 17 healthy volunteers and 5 patients with postsurgical gastroparesis. The barostat measures tone by monitoring the volume of air within a flaccid intragastric bag, maintained at a constant, preselected pressure level by an electronic feedback mechanism. In healthy individuals, inter-digestive variations in gastric tone were phase-locked in advance of duodenal interdigestive motor activity and consisted of three sequential periods; a quiescence period, an intermediate period, and a period of activity. In contrast to controls, gastroparetic patients presented significantly larger intragastric volume at low intragastric pressure (6 mmHg). Gastric distention (14 mmHg) resulted in significantly reduced extension ratio and phasic motor response in the gastric remnant. Furthermore, distention elicited a symptomatic response that resembled their postcibal syndrome (epigastric fullness, pain, nausea). These data suggest that postsurgical gastroparesis is associated with impaired tone of the residual gastric pouch.