The pancreatic component of the multiple endocrine neoplasia type I (MEN I) syndrome is a difficult and controversial problem because the entire endocrine pancreas is diffusely involved with varying degrees of islet-cell hyperplasia, microadenomatosis, and nesidioblastosis. In addition, in patients with functional syndromes, islet-cell tumors usually develop, and these may or may not be malignant. Because of the presumed inability to alleviate or cure the Zollinger-Ellison syndrome (ZES) in MEN patients, total gastrectomy was the treatment of choice before the introduction of H2 antagonists and omeprazole. At present, many physicians and surgeons consider H2 antagonists the best treatment and advise pancreatic exploration only when a gross pancreatic tumor is demonstrated on imaging studies. During the past 10 years we have studied all MEN I patients with ZES without hepatic metastases or gross pancreatic tumors using percutaneous transhepatic selective venous gastrin samplings. Two patterns of gastrin secretion were identified: (1) diffuse from multiple pancreatic sites and (2) localized regional secretion. Four patients from the latter group were selected for attempted surgical "cure" without gastrectomy or total pancreatectomy. Two additional patients are included who had resection of gastrinomas and have maintained basal serum gastrin levels within the normal range for extended periods. The follow-up on these patients ranges from 5 months to 12 years. All six patients have normal basal gastrin values, and those with remaining stomachs require no drug therapy.