Introduction: The accuracy of cerebrospinal fluid (CSF) biomarkers for detecting Alzheimer's disease (AD) pathology has not been fully validated in autopsied nonamnestic dementias. Methods: We retrospectively evaluated CSF amyloid beta 1-42, phosphorylated-tau, and amyloid-tau index as predictors of Alzheimer pathology in patients with primary progressive aphasia, frontotemporal dementia, and progressive supranuclear palsy. Results: Nineteen nonamnestic autopsied cases with relevant CSF values were included. At autopsy, nine had AD and 10 had non-AD pathologies. All six patients whose combined CSF phosphorylatedtau and amyloid b levels were "consistent with AD" had postmortem Alzheimer pathology. The two patients whose biomarker values were "not consistent with AD" had non-AD pathologies. The CSF values of the remaining eight non-AD cases were in conflicting or borderline ranges. Discussion: CSF biomarkers reliably identified Alzheimer pathology in nonamnestic dementias and may be useful as a screening measure for inclusion of nonamnestic cases into Alzheimer's trials. (C) 2017 the Alzheimer's Association. Published by Elsevier Inc. All rights reserved.