This report summarizes the neuropathologic findings in the first 106 autopsies of CERAD (Consortium to Establish a Registry for Alzheimer's Disease) dementia patients diagnosed clinically as having Alzheimer's disease (AD). In 92 (87%) of the 106 cases, neuropathologists confirmed Alzheimer's disease (AD) as the primary dementing illness. Coexistent Parkinson's disease (PD) changes were present in 19 (21%) and vascular lesions of varying nature and size in 26 (28%) of these 92 AD cases. The 14 cases in which AD was not interpreted as the primary dementing illness can be divided into four major subgroups based on their neuropathology findings: PD and related pathology (n = 5), hippocampal sclerosis (n = 3), miscellaneous neurodegenerative and other disorders (n = 3), and no significant changes (n = 3). Despite the relatively high level of clinical diagnostic accuracy, further refinement of assessment batteries may facilitate distinction of non-AD dementias from AD.