DISEASE CHARACTERISTICS: Histologically or cytologically proven acute lymphoblastic leukemia (ALL) No mature B-cell ALL (i.e., surface immunoglobulin present and L3 morphology) Standard risk disease at diagnosis defined as: 1 to 9 years at diagnosis Highest pretreatment WBC less than 50,000/mm3 No blasts on CSF cytospin No T-cell markers on lymphoblasts No anterior mediastinal mass No cranial nerve palsy High risk disease defined as any patient who fails to meet all standard risk criteria at either diagnosis or at end of induction No t(8;14) (q24;q32), t(8;22), or t(2;8) T-cell surface markers and t(8;14) (q24;q11) allowed Investigational Window eligibility: At least 30 days since prior steroid therapy No concurrent emergent mediastinal radiotherapy or intubation No septic shock No concurrent intracranial hemorrhage No clinical evidence of CNS or lung leukostasis Bilirubin less than 1.4 mg/dL

PATIENT CHARACTERISTICS: Age: 1 to 17 Performance status: Not specified Hematopoietic: See Disease Characteristics Hepatic: See Disease Characteristics Renal: Not specified Other: HIV negative

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior biologic therapy Chemotherapy: No prior chemotherapy Endocrine therapy: See Disease Characteristics No more than 1 week of steroids Radiotherapy: See Disease Characteristics Prior emergent radiotherapy to the mediastinum allowed Surgery: Not specified Other: Prior leukapheresis or exchange transfusion allowed, but must be completed before study