Purpose: To describe oral health and hygiene in old home care clients and investigate how functional ability was associated with them. Materials and Methods: This study employed part of the baseline data of a multidisciplinary intervention study of 269 home care clients aged ≥75 years, living in Eastern and Central Finland. Structured interviews were used to measure ability to function in activities of daily living (ADL), instrumental activities of daily living (IADL), comorbidity (functional comorbidity index, FCI), depression (geriatric depression scale, GDS-15), cognitive function (mini-mental state examination, MMSE), nutritional status (mini nutritional assessment, MNA) and numbers of prescription drugs used. Clinical oral examination was included. Results: The majority of participants were at least moderately dependent on support for ADL. Of the examined, 46% were edentulous and average number of teeth was 8.4. Dental plaque in ≥ 20% of teeth present was detected in 74%, bleeding on probing in ≥ 25% of teeth examined in 75%, and caries in 30% of the dentate participants. In multivariate analyses, better functional ability (ADL) was statistically significantly associated with lower occurrence of dental plaque in ≥ 20% of teeth present. Better functional ability (ADL) and higher number of teeth were associated with lower occurrence of bleeding on probing in ≥ 25% of teeth examined and higher number of teeth with plaque with higher occurrence of bleeding on probing. Conclusion: Impaired functional ability is an important determinant of poor oral health and hygiene among old home care clients.