 Brain tumors are the leading cause of death and disability from childhood disease in developed countries. With treatment advances over the last 25 years, survival rates have improved dramatically. However, survival is often achieved at considerable cost. Cranial radiation is frequently required for effective tumor control, and is associated with significant neuro-toxicity, including white matter damage and cognitive morbidity. In order to achieve the best possible outcome for survivors, and ultimately conquer the long-term consequences of this disease, new interventions must be developed to ameliorate the neuro-toxic effects experienced by children. radiation injury can now be used to guide the development of interventions designed to rescue neural tissue. Furthermore, various new agents and activities with potential to stimulate neuro-recovery are now available. The potential value of exercise for rescuing the brain from neuro-toxic effects, for instance, has recently been reported. Next, neuro-cognitive processes that are particularly sensitive to the effects of cranial radiation have been identified and can serve as behavioral assays to test the effectiveness of these new interventions. Finally, novel neuro-imaging tools are available to perform in vivo evaluations in order to delineate potential mechanisms of neuro-recovery. We intend to integrate these new research findings to develop and evaluate a physical exercise-based intervention targeted at rescuing brain tissue of children with brain tumors from the neuro-toxic impact of cranial radiation. 