Parenteral administration of amino acids has been utilized for the nutritional support of patients with a variety of gastrointestinal disorders including protracted pancreatitis and pancreatic fistulae. However, the effect of parenteral amino acid administration alone on human pancreatic secretion has not been studied. We have studied the short-term effect of parenteral administration of amino acids on pancreatic exocrine secretion in seven healthy men. A double-lumen tube was placed in the duodenum and polyethylene glycol was perfused into the proximal duodenum at the rate of 10 ml/min. A second double-lumen tube was placed in the stomach and bromsulfthalein was perfused into the cardia. Samples of duodenal contents were aspirated and gastric contents recovered during one hour of intravenous saline infusion followed by two hours of an amino acid mixture infusion. Hourly outputs of protein and pancreatic enzymes were determined, correcting for duodenogastric reflux based on concentrations of both markers in the samples. Despite an average increase of 72% in the plasma concentration of the infused amino acids, the outputs of protein, trypsin and amylase did not change significantly during amino acid infusion; the output of lipase decreased significantly during amino acid infusion. Two subjects were given intravenous secretin and cholecystokinin following amino acids; this resulted in increased outputs of protein, trypsin, and amylase in both. We conclude that the parenteral administration of amino acids to healthy young men does not stimulate pancreatic enzyme secretion as measured by the method using duodenal marker perfusion at the rate of 10 ml/min.