A high incidence of limitations in daily functioning is seen in older adults with intellectual disabilities (ID), along with poor physical fitness levels. The aim of this study was to assess the predictive value of physical fitness for daily functioning after 3 years, in 602 older adults with borderline to profound ID (>= 50 years). At baseline, physical fitness levels and daily functioning (operationalized as basic activities of daily living [ADL] and mobility) were assessed. After 3 years, the measurements of daily functioning were repeated. At follow-up, 12.6% of the participants were completely independent in ADL and 48.5% had no mobility limitations. More than half of the participants (54.8%) declined in their ability to perform ADL and 37.5% declined in their mobility. Manual dexterity, visual reaction time, balance, comfortable and fast gait speed, muscular endurance, and cardiorespiratory fitness were significant predictors for a decline in ADL. For a decline in mobility, manual dexterity, balance, comfortable and fast walking speed, grip strength, muscular endurance, and cardiorespiratory fitness were all significant predictors. This proves the predictive validity of these physical fitness tests for daily functioning and stresses the importance of using physical fitness tests and implementing physical fitness enhancing programs in the care for older adults with ID. (C) 2014 Elsevier Ltd. All rights reserved.