6. In patients with acute leukemia or CML in blastic crisis, intrathecal methotrexate administration will be resumed after the patient recovered platelet count to over 50,000/㎕. Methotrexate 10 ㎎/㎡ (not to exceed 12 ㎎ total) will be given intrathecally once every 2 weeks for three times (total four doses including one given before preparatory regimen). Folinic acid 15 ㎎ will be given p.o. or i.v. 24 hours after intrathecal methotrexate and q 6 hours for a total of 4 doses.