Several studies in recent years have addressed the accuracy of the clinical diagnosis of Alzheimer's disease (AD). However, most large studies have been done in university centers specializing in dementia. The purpose of this study was to assess the diagnostic accuracy of dementia in a community-based brain bank program, using data from the Central Florida component of the State of Florida's Brain Bank Program. Since 1987, 261 cases of dementia have been assessed at antopsy, and the clinical and pathologic diagnoses were compared. Of 234 patients with a clinical diagnosis of AD, 181 (77%) had a pathologic diagnosis of AD, with or without other contributing disorders. Of 27 patients with a clinical diagnosis of non-AD dementia, 14 (52%) had a pathologic diagnosis of AD, with or without other contributing diagnoses. These findings are similar to those previously reported and emphasize the importance of autopsy for the accurate diagnosis of dementia for genetic counseling, assessment of diagnostic techniques or drug therapy, and epidemiologic studies.