A-36-year-old male diagnosed with acute myelogenous leukemia (AML, M2) failed to achieve a complete remission after having undergone two courses of induction chemotherapy (idarubicin hydrochloride + cytarabine, high-dose cytarabine), and moreover, his cerebrospinal fluid (CSF) then revealed abnormal blasts. Dosages of 30 mg of methotrexate, 80 mg of cytarabine, and 40 mg of prednisolone acetate were given via lumbar puncture, and following this treatment, the leukemic cells were no longer detectable in his CSF. As a prophylaxis for meningeal leukemia relapse, he continued to receive intrathecal chemotherapy (methotrexate, prednisolone acetate) twice a week, and later he underwent reinduction therapy (second high-dose cytarabine). He displayed mental disorientation on the thirty-seventh day after he had been given a high-dose of cytarabine (araC). Up to the thirty-seventh day, he had also been given a total of 135 mg of intrathecal methotrexate. On the thirty-ninth day he fell into a coma, and his brain computed tomography (CT) demonstrated low density areas in the white matter, in addition to edema. These findings were compatible with leukoencephalopathy. With the administration of glycerin and methylprednisolone, his condition, however, began to reverse, and by the fifty-third day his brain edema had subsided and his mental condition had improved. On the ninetieth day he began to walk without assistance, and after the third course of re-induction chemotherapy, he achieved complete remission. He is currently doing well.