Vasoactive intestinal polypeptide (VIP) is a peptide hormone containing 28 amino acid residues and is produced in many areas of the human body including the gut, pancreas and suprachiasmatic nuclei of the hypothalamus in the brain. It acts as a neuromodulator and neurotransmitter and has many functions; It helps control or send nerve signals, relaxes certain muscles along the gastrointestinal tract, increases the amount of water and electrolytes released from the pancreas and gut, it triggers the release of hormones from the pancreas, gut, and hypothalamus, helps breakdown fat and glycogen, stimulates bile flow, and blocks gastrin and gastric acid secretion. HIGH levels of VIP are associated with Verner-Morrison syndrome which is due to VIPoma - a very rare type of cancer that usually grows from certain cells in the pancreas. Increased levels may also occur in patients with cutaneous mastocytoma and severe hepatic failure.