Dementia is quite common in the elderly. There are quite a lot of researches on dementia in Vietnam and other country. However, there are not many studies on the prevalence of dementia and related factors at the geriatric clinic, whe-re elderly patients are examined. Objective: To identify the prevalence of dementia based on MMSE in elderly at the Geriatric Clinic, University Medical Center HCMC. Methods: 387 elderly patients (≥ 60 years) were admitted to the Geriatric Clinic, University Medical Center HCMC during September 2019 to May 2020. The study design is a descriptive cross-sectional study. Results: The mean age of the study is 70.58 ± 6.94 years. The prevalence of dementia was 22.2%, with 73.3% being mild dementia, 25.6% moderate and 1.2% severe. Of which 73.3% was mild dementia, 25.6% was middle dementia and 1.2% was severe dementia. Conclusions: The prevalence of dementia at the Geriatric Clinic, University Medical Center HCMC was 22.2%. Therefore, it is necessary to screen for dementia in elderly patients at the Geriatric Clinic, University Medical Center HCMC, contributing to early detection of dementia in elderly patients to have an effective intervention strategy, improve quality living standards, as well as reducing the serious consequences of dementia for the elderly, family and society.