The recognition in recent years of the association of islet-cell tumors of the pancreas and gastric hypersecretion has been followed by reports of an increasing number of patients manifesting this condition by recurrent gastrointestinal ulcer disease or, in fewer patients, by an intractable diarrhea.1,2 These patients characteristically produce an overnight volume of gastric juice in excess of a liter, containing over 100 mEq. per liter of free hydrochloric acid. The ulcer disease is frequently fulminant with recurrent life-endangering duodenal, jejunal, or marginal ulceration, and the diarrhea can be sufficiently severe to produce death. Experience has shown that in at least 50% of patients the islet-cell tumors are malignant, about 20% are located in aberrant locations, about 10% consist of a diffuse adenomatosis, and approximately 20% are associated with polyglandular endocrine disease.3 Some, but not all, experimental evidence reported indicates that extracts of the tumors do stimulate gastric secretion.