Dasatinib treatment was superior to imatinib in a study of pediatric patients with Philadelphia chromosome-positive acute lymphocytic leukemia (ALL). Patients with Philadelphia chromosome-positive ALL aged zero to 18 years were randomized to receive a daily dosage of either dasatinib 80 mg/m2 (n=92) or imatinib 300 mg/m2 (n=97). After a median follow-up of 26.4 months, the four-year event-free survival rates were 71.0% in the dasatinib group and 48.9% in the imatinib group; overall survival rates were 88.4% and 69.2%, respectively. The four-year cumulative risk of any relapse was significantly lower in the dasatinib group than the imatinib group (19.8% vs. 34.4%), as was the four-year cumulative risk of an isolated central nervous system relapse (2.7% vs. 8.4%). Severe toxic effect rates did not largely differ between the groups.