Nine patients with the Zollinger-Ellison syndrome seen at a single referral centre between 1976 and 1981 are presented to highlight changes in the recognition, diagnosis and management of the condition. Less well recognized manifestations such as diarrhoea and features of the multiple endocrine neoplasia (MEN) type I syndrome are described, and the simplification of the pre-operative diagnosis by the use of both the serum gastrin estimation and the secretin provocation test considered. The problem of tumour localization is discussed with special reference to the newer techniques such as ultrasound, endoscopic retrograde cholangiopancreatography (ERCP) and CAT scanning, and the value of arteriography confirmed. The striking advances in management during the past few years are stressed with special reference to the role of the H2-receptor blocking drugs. Despite their profound inhibitory effect on both acid secretion and symptoms, all patients with the exception of those with proven metastases or the MEN type I syndrome underwent laparotomy to exclude a resectable lesion. If no resectable lesion was found truncal vagotomy was performed to facilitate acid secretory control post-operatively and H2-receptor blocking drugs continued in a dose necessary to maintain basal acid secretion under 5 mmol/hr.