Intestinal control of gastric secretion and emptying were studied in healthy humans by using intubation-marker-perfusion techniques. An occluding balloon was used to separate the jejunoileal test segment from the more proximal gut. Mixed-nutrient, semielemental meals (300 and 600 calories) were administered while varying the jejunal perfusate: normal saline, jejunal chyme or its protein (casein hydrolysate), lipid (oleic acid), or carbohydrate (maltose) components. The meal in contact with the stomach and duodenum increased gastric secretion above fasting levels. This was partially inhibited by whole chyme in contact with the jejunum, the lipid and carbohydrate components of chyme mediating this inhibition. Jejunoileal chyme inhibited gastric emptying, with all three nutrient components acting as inhibitors. Effects on gastric secretion and emptying were dose-dependent, being greater after the larger meal and most prominent in the early postprandial period; these effects on gastric emptying were more prominent than those on gastric secretion. These results suggest that the intestinal phase of gastric function is directed mainly toward regulation of the reservoir function of the stomach: to adapt the gastric delivery of nutrients and fluid to the capability for efficient digestion and absorption.