We examined corticotropin-releasing hormone-like immunoreactivity (CRH-LI) and corticotropin (ACTH) levels in the CSF of 33 patients with presumptive Alzheimer's disease (AD) and 13 healthy, age-matched controls. The mean CRH-LI and ACTH levels of the AD patients were significantly less than controls. Despite these reductions, none of the patients had evidence of pituitary-adrenal dysfunction. A disorder of extrahypothalamic CRH may be involved in the pathophysiology of AD.