Between 1986 and 1990, four children with recurrent CNS leukemia who had previous CNS prophylaxis therapy were treated with intermittent central nervous system irradiation and intrathecal chemotherapy (IIIC). There was no isolated CNS recurrence. One patient died form bone marrow relapse. Three patients are alive without evidence of disease for 3E3/12 year to 3E6/12 year after the diagnosis of recurrence of CNS leukemia. This experience suggests that IIIC may be an effective treatment for preventing the recurrence of CNS leukemia without any serious side effects.