Our findings to date indicate that: A peptide resembling oCRF is present in human and mammalian hypothalamus. oCRF is present in human lumbar cerebrospinal fluid. oCRF concentrations do not differ in CSF from normal individuals and from patients with Cushing's syndrome. oCRF appears to be synthesized via a large oligopeptide precursor. An oCRF-like molecule (oCRF-LI) is present in hypothalamic brain tissue. We have also observed more tentative evidence of low levels of oCRF-LI outside of the brain. oCRF is likely to be a central mediator of stress in its multiple forms. We believe that oCRF is clearly of major physiological importance, but that many critical unanswered questions remain. Probably, the most fascinating of these, which we are only beginning to comprehend, concerns the functions of CRF in extrahypothalamic brain as well as the CRF which appears to be present outside the brain.