Endocrine paraneoplastic syndromes result from the production of bioactive substances from neoplastic cells, of endocrine or neuroendocrine origin. Typically these are located in the lungs, the gastrointestinal tract, pancreas, thyroid gland, adrenal medulla, skin, prostate or breast. In endocrine paraneoplastic syndromes the secretion of peptides, amines or other bioactive substances is always ectopic and not related to the anatomical source. The clinical presentation, however, is indistinguishable from a suspected eutopic endocrine tumor posing a diagnostic challenge. The most common endocrine paraneoplastic syndromes are based on the secretion of antidiuretic hormone (ADH) resulting in hyponatremia, secretion of adrenocorticotropic hormone (ACTH) or rarely corticotropin-releasing hormone (CRH) resulting in Cushing syndrome as well as secretion of growth hormone-releasing hormone resulting in acromegaly. Paraneoplastic endocrine syndromes mainly occur in highly malignant tumors; however, the development of these tumors does not necessarily correlate with tumor stage, malignant potential or prognosis. As endocrine paraneoplastic syndromes are a rare complication, there are hardly any evidence-based therapeutic recommendations. Treatment of the underlying tumor is the first choice and in a palliative setting symptomatic therapy is possible.