A 55-year-old woman, known with multiple endocrine neoplasia (MEN) type 1, had rectal bleeding and later haematemesis but colonoscopy and gastroduodenoscopy revealed no abnormalities. Due to the normal results for serum gastrin concentration, gastroduodenoscopy and CT scanning of the pancreas, Zollinger-Ellison syndrome was considered to be less likely. Yet the diagnosis could be established on the basis of persistent symptoms and a positive somatostatin receptor scintigraphy. The patient was treated with high doses of a proton pump inhibitor and temporary tube feeding due to weight loss. Follow-up will take place at the endocrinology outpatients' department. Zollinger-Ellison syndrome is a relatively common feature of patients with MEN-1. The diagnosis and localisation of the gastrinoma can be difficult: serum gastrin concentrations can be normal and the sensitivity of CT scanning is low. The primary aim of treating gastrinoma is to control gastric acid hypersecretion by means of high doses of a proton pump inhibitor. The question as to whether surgery is indicated remains controversial.