BCR-ABL fusion gene t(9;22)(q34;q11) occurs in only 3% of pediatric acute lymphoblastic leukemia (ALL) cases. Previously, less than 40% of Philadelphia-positive ALL patients were cured with intensive chemotherapy. The use of imatinib (340 mg/m2/day) added to an intensive chemotherapy regimen has improved the outcome in this population at 3 years to an event-free survival of 80%. Imatinib treatment alone was administered after remission induction chemotherapy to a patient with Philadelphia-positive ALL who presented with serious chemotherapy toxicity, so that intensive chemotherapy could not be maintained. This is the only patient in the literature who survived remission for more than 2.5 years with imatinib treatment only.