The objective of this cross-sectional study was to describe the charafteristics of the epidemiology of dementia in the elderlyin two suburban communes in the Socson districtand two urban wards of the Dongda district in Hanoi. A total of 1.767 elderly people from 60 yaars old to older without obvious physical defects such as loss of hearing, loss of vision, or paralysis were recruited for the study. The average prevalence for dementia was 4.24 percent among the elderly participants. The prevalence for dementia was different between the elderly living in the Soc Son and Dong Da districts. A higher rate for dementia was observed in the elderly population living in the Soc Son district (5.06 percent) compared to only 3.56 percent for the elderly living in the Dong Da district. In addition the higher the age of the participants, the higher the rate of dementia. Prevalence rate for dementia was reduced among the elderly with a higher education. A history of cerebral vascular accident (20.8 percent), personal history of memory impairment (8.5 percent),anda family history of memory impairment (8.1 percent) were observed to be important factors in causing dementia in these two populations.