A severe ulcer diathesis may be caused by a hormone secreted by the non-beta cells of the pancreatic islets. This hormone stimulates the parietal cells to hypersecrete. Secondary changes observed by roentgenography consist of increased bowel fluid, ulceration, edema, dilatation, gastric and duodenal hypomotility, and jejunal hypermotility. These changes are often distinct enough to suggest the diagnosis of Zollinger-Ellison syndrome. An accurate preoperative diagnosis of this condition is important if the proper ablative therapy is to be carried out.