We report the case of a 43 year old man with multiple endocrine neoplasia (Zollinger-Ellison syndrome-hyperparathyroidism) diagnosed during investigations for a severe ulcer with diarrhoea. The history suggested Zollinger-Ellison syndrome, especially as basal acid production and blood gastrin levels were high. Hypercalcaemia and low blood phosphate levels suggested hyperparathyroidism, which was confirmed by ultra-sound of the neck, showing two parathyroid adenomas. The aim of treatment was two-fold: suppress the hyperparathyroidism and treat the Zollinger-Ellison syndrome. The approach is surgical in most cases, but the tumour is often impossible to remove and total gastrectomy has become rare with the progress in anti-secretory therapy. When the tumour behind a case of Zollinger-Ellison syndrome cannot be found, complementary chemotherapy is indicated. Other endocrine lesions must always be sought and the family investigated to exclude Wermer syndrome.