Neuropathologic confirmation is required to validate the NINCDS-ADRDA Work Group criteria for the clinical diagnosis of Alzheimer's disease (AD). Neuropathologic inclusion and exclusion criteria for AD, however, are not uniform. The purpose of this investigation was to examine the confirmation rate for the Work Group criteria against differing neuropathologic criteria for AD. The sample consisted of 57 cases, 22 of which had received a clinical diagnosis of AD. Nine neuropathologic criteria for AD were applied in a blind fashion to each of the 57 cases. Our results indicated that, depending on the neuropathologic criteria applied, the clinicopathologic agreement ranged from 64% to 86%. These findings demonstrate the need for universally accepted neuropathologic and clinical criteria for AD.