Multiple Endocrine Neoplasia Type 1 (MEN 1) is an autosomal dominant disorder resulting from inactivating mutations of the MEN1 tumour suppressor gene. Disease penetrance in MEN 1 is almost universal, with most patients developing primary conditions such as hyperparathyroidism (>95%), pituitary tumours(~25%) and gastroenteropanceatic neuroendocrine tumours (GEP NETs) in up to 70%. Functioning GEP NETs associated with clinical syndromes typically relate to pancreatic insulinoma and glucagonoma, with hypergastrinaemia arising from duodenal submucosal lesions. Non-functioning tumours are typically pNETs, with the addition of gastric carcinoid tumours developing in the context of pre-existing hypergastrinaemia. GEP NETs in MEN 1 typically follow an indolent, albeit potentially malignant and ultimately metastatic course (in up to 50% of patients), although a minority of both functioning and non-functioning NETs have an initially aggressive natural history. Diagnosis and evaluation of GEP NETs in MEN 1 requires biochemical confirmation and lesion localisation with anatomical (US, EUS, CT or MRI) and functional (PET) imaging. Treatment strategies for the various tumour subtypes are similar to those recommended for non-familial disease; the notable exceptions being gastrinoma and small (<2cm) non-functioning pancreatic NETs, where medical and conservative management strategies respectively are preferable. Hypergastrinaemia in MEN 1 is almost universally due to multicentric primary duodenal lesions are not amenable to definitive surgical resection. The indolent natural history of these NETs in conjunction with their excellent response to long-term somatostatin analogue therapy plus control of any residual gastric hyperacidity with proton pump inhibitors, makes for a good long term survival prognosis in many patients. Similarly, “multinodular pancreas” due to small, non-progressive and hormonally non-syndromic benign NETs favours surveillance without treatment for small pancreatic nodules. Treatment of functioning pancreatic tumours (typically insulinoma and glucagonoma) associated with a hypersecretory syndrome requires lesion resection, whilst aggressive irresectable and metastatic GEP NETs should be considered for standard management strategies (PRRT, TKI, mTOR inhibitors and Chemotherapy).