Significance: Yoga has the potential to significantly reduce fatigue, a prevalent and distressing symptom, in children with cancer and HSCT. The investigators have assembled the optimal team with the expertise and track record to accomplish this important trial. This trial is an incremental and critically important step in a program of research designed to improve health for children at highest risk for poor quality of life. Results may have broad applicability to other hospitalized pediatric populations and has the potential to change in-hospital care for these patients.