Recent progress in the treatment of acute leukemia is so rapid and wide-ranged that it is difficult to detail the progress. Therefore we limit this paper focusing following items: 1) FAB classification and therapeutic response; 2) 5000 leukocyte differential and survival; 3) bone marrow transplantation; and 4) over all survival and 5-year survival. 1) FAB classification and therapeutic response: 59 cases of acute non-lymphocytic leukemia were classified according to FAB classification: (M5-16 cases. The differences in the complete remission rate, duration of remission and median survival were not significant among these groups. 2) 5000 leukocyte differential and survival: 86 cases with acute leukemia which achieved complete remission were divided into three groups according to the levels of remaining leukemic cells by 5000 leukocyte differential: 0-1/5000-39 cases, 2-4/5000-24 cases and 5-/5000-23 cases. A close correlation between the leukemic cell level during remission and survival of patients was observed. A marked tendency of longer survival was observed in cases in which leukemic cells decreased during remission and vice versa. 3) Bone marrow transplantation (BMT) therapy: Up to now, 15 patients have been treated and 4 of them are alive now. The longest survival is a case of a 9 year old boy with ALL, who is doing well after BMT for one year and a half. 4) Median survival and 5-year survival: Overall median survival of acute leukemia patients was 7 months (1970-1974) and 12 months (1975-1979). We have experienced 12 patients of 5-year survivors. Out of them, 7 patients are still in remission for more than 6 years. The 5-year survival rate was 0.5% before 1969, and 8.3% after 1970. This indicates a remarkable improvement in the treatment of acute leukemia.