BACKGROUND: Young adult survivors of childhood brain tumors (BTs) may have late effects that compromise physical performance and everyday task participation. The objective of this study was to evaluate muscle strength, fitness, physical performance, and task participation among adult survivors of childhood BTs. METHODS: In-home evaluations and interviews were conducted for 156 participants (54% men). Results on measures of muscle strength, fitness, physical performance, and participation were compared between BT survivors and members of a population-based comparison group by using chi-square statistics and 2-sample t tests. Associations between late effects and physical performance and between physical performance and participation were evaluated in regression models. RESULTS: The median age of BT survivors was 22 years (range, 18-58 years) at the time of the current evaluation, and they had survived for a median of 14.7 years (range, 6.5-45.9 years) postdiagnosis. Survivors had lower estimates of grip strength (women, 24.7±9.2 kg vs 31.5±5.8 kg; men, 39.0±12.2 kg vs 53.0±10.1 kg), knee extension strength (women, 246.6±95.5 Newtons [N] vs 331.5±5.8 N; men, 304.7±116.4 N vs 466.6±92.1 N), and peak oxygen uptake (women, 25.1±8.8 mL/kg per minute vs 31.3±5.1 mL/kg per minute; men, 24.6±9.5 mL/kg per minute vs 33.2±3.4 mL/kg per minute) than members of the population-based comparison group. Physical performance was lower among survivors and was associated with not living independently (odds ratio [OR], 5.0; 95% confidence interval [CI], 2.0-12.2) and not attending college (OR, 2.3; 95% CI 1.2-4.4). CONCLUSIONS: Muscle strength and fitness values among BT survivors were similar to those among individuals aged ≥60 years and were associated with physical performance limitations. Physical performance limitations were associated with poor outcomes in home and school environments. The current data indicated an opportunity for interventions targeted at improving long-term physical function in this survivor population. © 2010 American Cancer Society.