This paper presents the updated Polish Neuroendocrine Tumour Network expert panel recommendations on the management of neuroendocrine neoplasms (NENs) of the stomach and duodenum, including gastrinoma. The recommendations discuss the epidemiology, pathogenesis and clinical presentation of these tumours as well as their diagnosis, including biochemical, histopathological and localisation diagnosis. The principles of treatment are discussed, including endoscopic, surgical, pharmacological and radionuclide treatment. Finally, recommendations on patient monitoring are given.