From 2/2003 to 2/2006, at Blood transfusion and Hematoglogy of HCM City, 44 children patient, whose were diagnosed acute lymphoblastic leukemia de novo and had complete remission after induction therapy with Fralle-2000 protocol, were treated high dose Methotrexate (5g / m2) combine with chemotherapy and intrathecal (MTX, Ara-C, Depomedrol) of post induction fralle-2000 protocol.