Multiple endocrine neoplasia type 1 (MEN1) gastro-entero-pancreatic (GEP) tumours develop from the pancreatic islets and from the endocrine cells of the duodenal and gastric mucosa. Even if GEP tumours have generally a benign course, a subgroup of them shows an aggressive behaviour and is a major cause of death amongst MEN1 patients. Diagnosis of insulinoma should lead promptly to pancreatic surgery. MEN1 gastrinomas are multiple and almost exclusively localized in the duodenum. Cure rate for Zollinger-Ellison syndrome in MEN1 is low when surgery is limited to tumour enucleation or full thickness duodenal wall resection. Conversely, pancreatoduodenectomy is followed by higher chance of cure. For nonfunctioning tumours exceeding 1 cm diameter in size a prompt treatment is recommended due to their high malignant potential. Gastroscopic surveillance is indicated for the frequent occurrence of multiple, small, type 2 fundic carcinoids. Endoscopic removal is possible for lesions growing in the mucosa-submucosa, but partial or even total gastrectomy is recommended for the small number of gastric carcinoids infiltrating the muscular layers.