CSF neurotransmitter markers may reflect neurochemical alterations in Alzheimer's disease (AD). The best studied neurochemical deficit in AD is that of acetylcholine. Both acetylcholinesterase and butyrylcholinesterase activity have been reported to be reduced in some but not all studies of AD CSF. Studies of monoamine metabolites have also been controversial but most authors have found reduced concentrations of CSF HVA, lesser reductions in HIAA and no change in MHPG. CSF GABA concentrations have been found to be reduced in AD. Studies of CSF neuropeptides in AD have shown reduced concentrations of somatostatin and vasopressin, normal concentrations of vasoactive intestinal polypeptide and either normal or decreased concentrations of beta-endorphin and corticotropin releasing factor. Although no individual CSF neurochemical markers are specific for AD it may be possible to develop a profile of several neurochemical markers which will have enhanced specificity.