The survival rates of patients with childhood cancer have substantially improved over the last decades. The number of long-term childhood cancer survivors has increased, therefore insights in the long-term sequelae of childhood cancer survivors become increasingly important. Osteonecrosis and low bone mineral density (BMD) are serious osteogenic side effects that can occur during or after acute lymphoblastic leukemia (ALL) treatment. Moreover, childhood cancer survivors also carry an increased risk for dysregulation of body-composition, which contributes to metabolic syndrome and increases the risk of cardiovascular disease. During this PhD project, we focus on the direct and long-term bone toxicity and altered body composition following childhood cancer treatment.