The cure rate for children with acute lymphoblastic leukemia in big treatment centers in Western countries is now about 80%. This accomplishment is owe to patients successful treatment based on combination of multiagent chemotherapy, risk-based intensification of therapy and central nerve system prophylaxis. Stratification of patients is according to prognostic factors that predict risk of relapse. It is necessary to consider the interrelationship of prognostic factors. In host-related factors, which are generally known as age, gender, race, and pharmacogenetics. Disease-related factors include white blood cell count, immunopheno typing, cytogenetic or molecular genetics features, etc. Treatment-related factors are what can be modified. Early response to treatment is often the strongest prognostic factor. Large, controlled and usually randomized clinical trials greatly improve the prognosis of childhood acute lymphoblastic leukemia.