Patients with coeliac disease have a highly significant reduction in the release of secretin and gastric inhibitory polypeptide from the upper small intestine, but a greatly increased release of enteroglucagon, and also of neurotensin, from the lower part of the small intestine. The release of gastrin and pancreatic polypeptide, from the antrum and pancreas respectively, is, however, normal. Thus the pattern of hormone release reflects the location of the mucosal lesion. The gut-hormone profile may also help to characterise other gastrointestinal diseases.