SUMMARYA man of 55 years presented with a Iz-year history of intermittent vomiting and in a semi-comatose state. H e had severe water and electrolyte disturbances, with a plasma chloride of 27 mEq./l., and a chloride deficit i n excess of 2500 mEq. ; he also had acid-base disturbances. Gastric acid studies suggested the possibility of the Zollinger-Ellison syndrome. At operation, the rare condition of congenital duodenal stenosis in an adult was found. H e made an uneventful recovery.CONGENITAL duodenal stenosis is rare, particularly when it presents in adults. T h e following report is of such a patient, who on investigation had some features suggestive of the Zollinger-Ellison syndrome. CASE REPORT Mr. B. L., a watchman aged 55 years, presented at the University Hospital in a semi-comatose state. The history was one of 12 years' intermittent abdominal pain and vomiting accompanied by visible peristalsis. The vomiting had got worse in the week preceding his admission.On examination, he was emaciated and responded only to painful stimuli. There was clinical evidence of severe body-fluid depletion, and his hands were in carpal spasm. His abdomen was distended and there was a succussion splash. Otherwise, no abnormality was detected on gcncral examination.A chest radiograph was normal and an abdominal radiograph showed features of pyloric obstruction, with a large stomach with fluid levels in the fundus and the pyloric antrum. Other investigations showed: haemoglobin, 13.5 g./Ioo ml. He was treated with gastric suction via nasogastric tube and intravenous replacement of fluid and electrolytes. During the first 24 hours there was no excretion of urine. (A catheter was placed in the bladder.) After this, he passed dilute urine. He regained consciousness and his carpal spasm disappeared within 24 hours of admission.Ten days after admission ascites and oedema of his legs were noted, but there was no other evidence of (Fig. I).Magnesium supplements were added to his regimc and within a few days the serum potassium and magnesium