Calcitonin gene-related peptide (CGRP) is a 37-residue peptide recently characterized in the brain and found in high concentrations in the gut, particularly in the stomach and pancreas. The effects of intravenous infusion of human and rat CGRP (260 pmol . kg-1 . h-1) on gastric secretion and emptying and pancreatic exocrine secretion were studied in conscious dogs. CGRP inhibited by 60-75% gastric acid secretion stimulated by a meal, sham feeding, or step doses of bombesin but did not modify acid response to step doses of histamine or bethanechol. The inhibitory effect of CGRP is not due to blockage of postprandial or bombesin-stimulated gastrin release. CGRP did not influence basal or meal-stimulated pancreatic exocrine secretion or the rate of gastric emptying of a saline meal. These results indicate that CGRP is a potent and selective inhibitor of gastrin-mediated acid secretion in dogs and, under these conditions, did not alter other gastrointestinal functions such as gastric emptying or pancreatic exocrine secretion.