AbstractThis ENETS guidance paper aims to provide practical advice to clinicians for the diagnosis, treatment and follow‐up of functioning syndromes in pancreatic neuroendocrine tumours (NET). A NET‐associated functioning syndrome is defined by the presence of a clinical syndrome combined with biochemical evidence of inappropriately elevated hormonal levels. Different hormonal syndromes can be encountered in pancreatic NET patients, including insulinoma, gastrinoma as well as the rare glucagonoma, VIPoma, ACTHoma, PTHrPoma, carcinoid syndrome, calcitoninoma, GHRHoma and somatostatinoma. The recommendations provided in this paper focus on the biochemical, genetic and imaging work‐up as well as therapeutic management of the individual hormonal syndromes in well‐differentiated, grade 1‐3, functioning NET with the primary tumour originating in the pancreas, and for specific subtypes also in the duodenum.