CRH is a 41-residue neuropeptide, which is mainly produced in the hypothalamus and acts as the principal neuroregulator on the secretion, among others, of adrenocorticotropic hormone (ACTH). CRH is considered to be the key-hormone in the control of the hypothalamic-pituitary-adrenal axis function and is responsible for the endocrine, autonomic, immunological and behavioural responses of mammalians to stress. The NMR solution structure of a synthetic analogue have been determined (PDB: 1GOE & 1GO9) and various new analogues have been synthesized.