Neuroendocrine neoplasias are seldom, but increasing. This holds true for the incidence but even more for the prevalence, since patients are able to live with their disease for quite a long time. The European Neuroendocrine Tumor Society (ENETS) as well as other societies (NANETS: North American Neuroendocrine Tumor Society; NCCN: National Comprehensive Cancer Network; ESMO: European Society of Medical Oncology) have published diagnostic and therapeutic guidelines that we present in this review. We aim to summarize those actual guidelines in a practice-based diagnostic and therapeutic algorithm, but also wish to point to open questions that have to be discussed in a multidisciplinary approach.