The number of very elderly people is increasing worldwide, so that the prevention of fractures and disability in this frail population has become a growing concern. This study evaluated the association between functional status and bone health in the oldest old. The study participants were of a very elderly population comprising 170 rural community dwellers, aged 80-107 years. Quantitative ultrasound (QUS) measurements were performed on both heels. Functional status was assessed by evaluating activities of daily living (ADL) and instrumental activities of daily living (IADL). Data on sociodemographic characteristics and potential risk factors, including medical history, smoking, alcohol intake, exercise, and physical activities were collected by trained interviewers. Generalized multiple linear regression suggested that disability was significantly associated with calcaneal QUS in the oldest old. After adjusting for the effect of potential covariates, such as age, gender, education level, weight, smoking, and physical activity level, the lowest tertile score groups of ADL and IADL were associated with a decrease in stiffness index (SI) T-score of calcaneal QUS. A complete ADL deficit was associated with a low QUS (adjusted beta vs. independent group=-1.17, 95% confidence interval=-2.01 to -0.33). Evidence of disability as an associated factor on bone health provides important insight to devise strategies for preventing or delaying further disablement among the elderly.