Octreotide (SMS 201-995, Sandostatin) is an octapeptide that exerts pharmacologic actions similar to the natural hormone, somatostatin. It was developed by Bauer and co-authors at Sandoz. It is an even more potent inhibitor of growth hormone, glucagon, and insulin than somatostatin. Like somatostatin, it also suppresses LH response to GnRH, decreases splanchnic blood flow, and inhibits release of serotonin, gastrin, vasoactive intestinal peptide, secretin, motilin, and pancreatic polypeptide. By virtue of these pharmacological actions, Sandostatin has been used to treat the symptoms associated with metastatic carcinoid tumors (flushing and diarrhea), and Vasoactive Intestinal Peptide (VIP) secreting adenomas (watery diarrhea). Sandostatin substantially reduces growth hormone and/or IGF-I (somatomedin C) levels in patients with acromegaly. A radioactively labelled analogue has been used to visualize somatostatin receptors in a GRF-secreting human tumour.