We compared the gastric, pancreatic, and biliary secretory responses to a liquid test meal and the rates of gastric emptying of liquid and solid test meals in six patients at least 1 year after parietal cell vagotomy with eight unoperated subjects, one with duodenal ulcer disease and seven normal control subjects. Parietal cell vagotomy decreased gastric acid secretion to one third of normal, but total trypsin and bile salt secretion during the first 150 postcibal minutes were normal. The liquid test meal emptied from the stomach faster after parietal cell vagotomy, the pattern of emptying being exponential in the vagotomy patients and linear in the normal subjects. The rate of gastric emptying of a liquid meal, although faster than normal, was less precipitous after parietal cell vagotomy than after truncal vagotomy plus drainage or subtotal gastrectomy, and trypsin and bile salt concentrations were not diluted to abnormal levels, as occurs after these other procedures. Furthermore, emptying and dispersion of solid food remained normal after parietal cell vagotomy. These findings probably explain, at least in part, the decreased incidence of postprandial dumping and diarrhea that accompanies parietal cell vagotomy compared with the other popular operations for duodenal ulcer.