Although abdominal complaints are frequent in both acute and chronic alcoholism, little is known of the effect of ingestion of ethanol with a meal on the function of the upper digestive tract. We have studied the effects of oral ethanol (1 g/kg body wt) taken with food on the gastric emptying rate of a solid-liquid meal as measured by a dual radioisotope technique in six normal subjects; and the gastric response (emptying and secretion), biliopancreatic secretions, and duodenal nutrient absorption after an homogenized meal, as evaluated by a gastroduodenal intubation-marker perfusion technique on seven healthy volunteers. In the latter experiments, radioimmunoassays of gastrin, secretin, cholecystokinin, pancreatic polypeptide, motilin, somatostatin, gastric inhibitory polypeptide, and vasoactive intestinal polypeptide were performed serially. As compared with the control experiment, alcohol induced the following effects: marked delay of gastric emptying of solids, smaller slowing effect on gastric emptying of the liquid phase of the solid-liquid meal and of the homogenized meal; no significant change in gastric acid secretion; no change in the overall postprandial pancreatic enzyme outputs, but a delay of lipase secretion; no change in the early bile salt postprandial output, but a reduced bile salt secretion from the second postprandial hour onwards; no significant change in carbohydrate and lipid duodenal absorption; and a significantly greater postcibal gastrin release. The mechanisms for these effects of alcohol on upper digestive tract function remain to be clarified.