A 12-year-old girl with acute non-lymphocytic leukemia was treated with a protocol involving high-dose cytosine arabinoside (Ara-C) for intensification of early therapy. The patient, who had been revealed to have CNS infiltration on admission, achieved complete remission after receiving ACMA/BHAC combination and intrathecal MTX. As an early intensification treatment, ID/HD Ara-C was safely and effectively administered; this consisted of ADR (45 mg/m2 iv) Day 1, intermediate-dose Ara-C (0.5 g/m2, 1-h drip, q. 12 h) Days 2-4, and high-dose Ara-C (3 g/m2, 3-h drip, q. 12 h) Days 10-11, followed by L-asp (6,000 U/m2, im) on Day 12. Ten months later, the patient has been in continuous complete remission. High-dose Ara-C should be included with caution as an early intensification of treatment to improve the therapeutic results of childhood ANLL.