Since October 1984, children with acute lymphoblastic leukemia (ALL) were treated with six protocols of the Kyushu-Yamaguchi Children's Cancer Study Group (KYCCSG). We reviewed cases in whom the first relapse sites of ALL were CNS, testis and ovary. Between October 1984 and July 1993, 302 children with ALL were registered. Ten children (3.3%) developed CNS-L. After treatment for CNS-L, four cases were alive, however one of them has had several episodes of CNS-L. Testicular relapse occurred in 8 boys and three of them are alive. One girl developed ovarian and uterine involvement 7 months after completion of treatment and she survived after intensive chemotherapy for an additional 3 years. Before September 1990, children with ALL received 18Gy cranial irradiation in standard risk group and 24Gy in high risk group. Since October 1990, children with ALL received no cranial irradiation in low risk group, 15Gy in intermediate risk group and 18Gy in high risk group. Incidence of CNS-L has not increased in children treated with protocols, in which cranial irradiation was reduced.