From June 1996 to January 2001, 91 patients with B-cell non-Hodgkin lymphoma or B-cell acute lymphoblastic leukemia up to 18 years of age were enrolled in Tokyo Children's Cancer Study Group (TCCSG) NHL B9604 protocol study. Five-day intensive chemotherapy courses including high-dose methotrexate and high-dose cyclophosphamide were used for localized disease (Groups A and B). High-dose cytarabine was added for advanced disease (Groups C and D). Fifteen patients experienced an adverse event. There were three induction failures, eight relapses (three local, four bone marrow (BM), one BM + local), two toxic deaths and two second malignant neoplasm. Event-free survival at 6 years in Group D and in all patients was 82.4% +/- 9.2% and 81.9% +/- 4.4%, respectively. The TCCSG NHL B9604 protocol achieved an excellent treatment outcome especially in patients with the most advanced disease (Group D: high BM blast cell burden and/or central nervous system involvement).