Laparotomy failed to show an obvious primary lesion in two patients with the Zollinger-Ellison syndrome (ZES), one of whom had metastatic gastrinoma in a solitary lymph node which was removed. Both patients underwent a truncal vagotomy and pyloroplasty. Postoperative acid studies have shown a marked and sustained diminution in acid hypersecretion which was particularly striking in the patient with a solitary metastatic lymph node. The patient without a detectable lesion is now well-controlled on half the dose of cimetidine required pre-operatively and the other no longer requires therapy. We believe that patients in whom pre-operative investigations have shown no evidence of extensive metastases should undergo laparotomy in the hope of finding a solitary primary or isolated metastatic lesions unassociated with an obvious primary in the pancreas. Available evidence suggests that simple removal of such lesions offers the patient an excellent chance of long-term remission. However, if no such lesion is discovered, vagotomy may be the logical procedure to assist in the subsequent pharmacological control of the acid hypersecretory state.