Cancer is the second most frequent cause of death in children. Leukemia accounts for nearly 40% of all childhood cancers. Prof. Akinobu Matsuzaki has investigated the treatment outcome of childhood acute lymphoblastic leukemia (ALL). During the past two decades, the long-term survival rates of ALL have improved from 67% to 86%, according to an increase in treatment intensity. The aims of treatment have thus shifted from palliation to cure. However, leukemia therapy during childhood may result in long-lasting functional deficits of some organs later in life. Treatment should be designed to produce maximum cure rates and minimum late adverse effects in survivors.