Gastroenteropancreatic neuroendocrine tumours (GEP NETs) represent a heterogenous family of tumours with growing incidence and challenging clinical management. Unlike other solid tumours, they have the ability to secrete different peptides and neuramines that cause distinct clinical syndromes. However, many are clinically silent until advanced disease. This guideline aims to provide practical recommendations for the diagnosis and treatment of GEP NETs. Most recent histological and staging classifications, as well as available therapeutic approaches, such as surgery, locoregional therapy, peptide receptor radionuclide therapy (PRRT) and hormonal or systemic therapy, are discussed in this manuscript, including some recent relevant achievements with novel targeted agents. Clinical presentation (with or without hormonal syndrome), histological tumour features (including proliferation index (Ki-67) and the presence or not of somatostatin receptors), tumour stage, and location of primary tumour and distant metastasis are all key issues that shall be taken into consideration to properly design and integrate the most adequate therapeutic strategy.