ABSTRACT Institutionalization has been associated with social isolation, psychological and cognitive changes, and decreased levels of physical activity in older adults. Objectives: The aim of this study was to estimate the prevalence of dementia, mild cognitive impairment (MCI), and functional dependence in older adults dwelling in two different Brazilian long-term care facilities (LTCFs). Methods: This is a cross-sectional study with 185 older people of both sexes, aged 60 years or over, residing in two LTCFs in the city of Montes Claros-MG, Brazil. The diagnosis of MCI and dementia was performed using the Diagnostic and Statistical Manual of Mental Disorders. Results: Prevalence rates of dementia, MCI, and functional dependence in institutionalized older participants were 62.3, 15.1, and 78.9%, respectively. There was a significant reduction of the Mini-Mental State Examination scores according to the increase of the institutionalization period in LCTFs and the age of older adults (p<0.001). Conclusions: Prevalence of dementia and functional dependence of older adults residing in LTCFs exhibited higher rates compared to the other older population worldwide. A higher institutionalization period is related to a greater cognitive decline.