Since 1970, the cure rate of acute lymphoblastic leukemia (ALL) inchildren has increased dramatically, from less than 30 percent toapproximately 80 percent. This remarkable improvement has resultedfrom the marriage of laboratory and clinical science. The identification ofeffective agents in randomized cooperative-group studies, the applicationof treatment to the central nervous system before the onset of symptoms,the intensification of treatment, and the use of "risk-adapted therapy"(therapy tailored to the predicted risk of relapse) have led to today'simpressive cure rates.