The authors report the incidence of dementia in a community-dwelling Brazilian population. In 1997, 1656 individuals aged 65 years or more, the majority being of very low educational level, were screened at their homes in Catanduva, Brazil, and dementia was diagnosed in 118 cases. The remaining 1538 individuals were rescreened 3.25 years later applying a health questionnaire, the Mini-Mental State Examination (MMSE) and the Pfeffer Functional Activities Questionnaire (PFAQ). According to PFAQ and MMSE scores, selected subjects were submitted to clinical, neurologic, and cognitive evaluations. The subjects diagnosed with dementia underwent laboratory tests and brain computed tomography. A total of 1119 individuals were rescreened and 50 incident cases of dementia (28 with Alzheimer disease [AD]) were identified. The incidence rate of dementia was 13.8 and of AD was 7.7 per 1000 person-years for individuals aged 65 years or older. The incidence rates of dementia almost doubled with every 5 years of age. There was no difference according to gender, but women had a higher incidence of dementia, predominantly AD, in very old age. There was a trend for higher incidence of dementia in illiterates (p = 0.07), but multivariate analysis disclosed significant association only between age and higher incidence of dementia. The incidence rates of dementia in this Brazilian community are comparable to those reported in Western and Asian studies.