OBJECTIVE: To analyse whether cognitive function and functional ability are related to oral health among community-dwelling older people over the age of 80 years. BACKGROUND: This cross-sectional study is based on the Kungsholmen Elders Oral Health Survey (KEOHS). The study included oral examinations carried out in two local clinics by standardised examiners and interviews using structured questionnaires. MATERIALS AND METHODS: Altogether 159 individuals were included in this study. Coronal caries and root caries were assessed using the National Institute of Dental and Craniofacial Research (NIDCR) diagnostic criteria. Cognitive function was assessed by the Mini-Mental State Examination (MMSE) index and functional ability was assessed by a global measure of self-reported changes. RESULTS: Older adults with a low MMSE score (< or = 23) tended to have a higher risk of coronal caries than those with higher scores. Participants with mild cognitive decline (MMSE = 24-26) and with a decrease in functional ability had a significantly higher risk of root caries. These associations changed little when adjusted by the covariates. In addition, people with a low MMSE (0-23) had a four times higher risk of not using dental services regularly. This result was unchanged after adjusting for the variables studied. CONCLUSIONS: This study revealed associations between the cognitive and functional status of the individual and aspects of oral health, that may contribute to a deeper understanding of the background of oral health status in older adults.