A retrospective study of 376 patients with dementia was performed to determine the rate of syphilis seropositivity. Subjects were seen over a 2.5-year period and received medical, social, psychiatric, neurological, and laboratory evaluations. Mean age was 74 years and 73% were women. Diagnoses included Alzheimer's disease (AD; 29.8%), vascular dementia (VascD; 24.7%), combined AD/VascD (14.3%), and other diagnoses (31.2%). Dementia was moderately advanced with a mean Folstein Mini-Mental State Score of 16. Fluorescent treponemal antibody absorption tests (FA) were performed on 338 of the patients with 10.9% being reactive. Two of nine subjects with reactive FA's had reactive rapid plasma reagin tests.