The purpose of this study was to determine if an eight-week intrahospital supervised, conditioning program improves functional capacity and quality of life (QOL) in children (4 boys, 4 girls) (mean [SD] age: 10.9 [2.8] years [range: 8-16]) who have undergone bone marrow transplantation (BMT) for leukemia treatment within the last 12 months. A group of 8 age and gender-matched healthy children served as controls. The experimental group performed 3 weekly sessions of resistance and aerobic training inside an intra-hospital gymnasium. A significant combined effect of group and time (p < 0.05) was observed for muscle functional capacity (Timed Up and Down Stairs [TUDS] test) and peak oxygen uptake (V.O(2peak)), i.e., with BMT children showing greater improvements than controls (V.O(2peak) at pre- and post-training of 25.9 (8.2) and 31.1 (7.6) mL/kg/min in diseased children). Muscle strength (6 RM test for bench and leg press and seated row) also improved after training (p < 0.05) in the BMT group. Concerning QOL, a significant combined effect of group and time (p < 0.05) was also observed for children's self-report of comfort and resilience and for parents' report of their children's satisfaction and achievement. In summary, children who have received BMT experience physical and overall health benefits after a relatively short-term (8 weeks) supervised exercise training program.