Background: Increased survivorship of childhood cancer has revealed a number of long-term morbidities related to treatment. Evidence suggests that cancer and its treatment may accelerate normal loss of physiologic capacity that occurs during aging.The advanced physiologic aging and related morbidities often seen in childhood cancer survivors suggests that these patients may present with signs of early-onset frailty. Frailty is a measure of global infirmity and impaired physical function and has been correlated with adverse health outcomes and elevated incidence of mortality in the general population. Research into the incidence and applicability of the frailty phenotype in children being treated for cancer may aid in the identification of the most vulnerable patients and identify those who may require intervention. The purpose of this study is to explore the frailty phenotype in children and adolescents receiving maintenance chemotherapy for acute lymphoblastic leukemia or lymphoma.