About 25% of patients with ZES have MEN-1. Except for diarrhoea, less frequent in patients with ZES MEN-1 than in sporadic ZES, and specific MEN-1-related signs, clinical characteristics are similar in both ZES types. Acid output and gastrin level are also similar whether in the basal state or after secretin. Primary hyperparathyroidism (pHPT) exists in the majority of ZES MEN-1 patients, 30% have pituitary adenoma (prolactinomas for half), 30% adrenal involvement, 25-30% have ECLomas: bronchial and thymic carcinoids have probably been underevaluated. Gastrinomas are multiple predominantly located in the duodenal wall, but also in the pancreas in association with clinically silent endocrine tumours. The spread of the disease metastases to the liver (LM), mediastinum, bones, is evaluated best by Octreoscan. Associated endoscopic ultrasonography evaluates the number, size and anatomical characteristics of gastrinomas. Patients without LM have an excellent prognosis. Surgery never cures ZES, but is necessary in cases of associated life-threatening conditions such as insulinoma. Although the size of the tumour, when located in the pancreas >3 cm, favours metachronous LM occurrence, surgery in our experience has not been able to prevent LM development.