Seventy-three children with acute nonlymphocytic leukemia (ANLL) have been treated with ANLL-85 and ANLL-88 protocol at Kyushu-Yamaguchi Children's Cancer Study Group between June, 1985 and February, 1993. Ten boys and 10 girls (0y4m-16ylm) were treated with the ANLL-85 protocol. The complete remission (CR) rate was 75% and the 5-year event free survival (EFS) was 20 +/- 9%. It was terminated because of frequent early relapse (within 6 months after CR). Thirty-four boys and 19 girls (0y3m-17ylm) were treated with the ANLL-88 protocol. The CR rate was 85% and the 5-year EFS was 32 +/- 7%. Early relapse rate with ANLL-88 was lower than that of ANLL-85, however 9 cases relapsed after terminating therapy. Although bone marrow transplantation (BMT) from related donors during the first CR was effective in ANLL-88, EFS was not improved. Recognition of risk factors and appropriate chemotherapy regimens with or without the support of stem cell transplantation may be necessary to cure children with ANLL.