Gastro-entero-pancreatic neuroendocrine tumours (GEP NETs) are unusual. Their incidence, the different tumour types and growth patterns are described. The tumours should be classified according to the WHO 2000 classification and the Tumour Node Metastasis classification according to guidelines from the European Neuroendocrine Tumour Society. Important parameters are localization, size, hormonal secretion, mitotic index, and proliferation index (Ki-67) of the primary tumour. Patients with GEP NET should be referred to as few centres as possible in order to obtain the highest experience and the greatest understanding of these tumours thereby achieving the capacity to offer patients the best possible treatment and to create optimal conditions for research.