In Lao PDR, measurement of cognitive function has rarely been conducted among elderly individuals. This study aimed to investigate the cognitive function among elderly individuals who lived at their homes with family in Lao PDR. Participants were elderly individuals aged 60 years or over registered with the local government in urban (Vientiane capital; VC) and rural areas (Khammouane province; KP). Those with serious mental/physical diseases, those who could not walk by themselves, or those who could not speak the Lao language were excluded. The information was collected through interviews with the participants and their family members. A newly developed Lao version of the Revised Hasegawa's Dementia Scale (HDS-R) was applied to measure cognitive function. The participants were 414 elderly individuals (224 males and 190 females) aged 60 to 98 years. The average HDS-R score was 23.0 among 115 men in VC, 22.7 among 92 women in VC, 20.3 among 109 men in KP, and 17.5 among 98 women in KP. The main caregiver was a daughter (40.6%) followed by a spouse (31.4%). Among 414 elderly individuals, 42 (10.0%) stated the necessity of support. Those with HDS-R < 20 accounted for 38.8% in men and 48.9% in women. The adjusted odds ratio of HDS-R < 20 was significant for those in rural areas (3.83) relative to those in urban areas. Among superficially healthy elderly individuals residing with their families, those with reduced cognitive function were more common among women and in rural areas.