Lipoprotein oxidation may play an important role in the pathogenesis of Alzheimer's Disease (AD), and therefore, we investigated cerebrospinal fluid (CSF) antibodies to oxidized low-density lipoprotein (OxLDL) in patients with AD and other neurodegenerative dementias. IgM and IgG antibody titers to OxLDL were measured in 50 CSF samples and 11 plasma samples using chemiluminescent ELISA. All CSF samples contained IgG antibodies, and also most IgM, binding to OxLDL. CSF antibodies to OxLDL were not related to CSF protein or albumin concentrations or plasma antibodies to OxLDL. Competition immunoassay for specificity demonstrated that about 50% of the CSF IgG binding to OxLDL was inhibited by soluble OxLDL. CSF IgG antibodies to OxLDL were significantly increased in AD patients compared to controls and to patients with frontotemporal lobar degeneration. The role of these antibodies in CSF is unknown and further investigations are needed.