Eighteen children with acute myeloid leukemia have been treated with a fourdrug protocol using cytosine arabinoside, daunorubicin, prednisolone, and mercaptopurine or thioguanine. The initial remission rate overall was 78%. Of 15 children who completed a week's treatment, i.e. one complete cycle, 14 entered complete remission (93%). The median survival was 7 months, and the median survival for those entering remission was 12 M months. Cancer 36:1547-1551, 1975. N CHILDREN, THE ACUTE NONLYMPHOBLASTIC I leukemias (e.g. myeloid, monocytic, erythroleukemia, etc.) are less common than lymphoblastic leukemia. The reported incidence has varied from 7.1%' to 31.6%.' Pierce et al." recorded 17.2% in their study of 1770 cases. In Manchester the Children's Tumour Registry records an incidence of 19% in the 465 children presenting with leukemia between 1954 and 1968.16 Impressive advances have been made in the management of acute lymphoblastic leukemia: initial remission rates of 90-100% are common," and 7-year survival rates of 17% have been reported. * Patients with the nonlymphoid acute leukemias have fared less well. There are fewer cases, initial remission rates are poorer, and total survival times are shorter. Our recent results with this group of leukemias have shown an encouraging improvement, which we report here. A group of 18 children has been treated with a four-drug protocol using cytosine arabinoside, daunorubicin, prednisolone, and 6-mercaptopurine or 6-thioguanine. The initial remission rate was 78%. Of 15 children who completed over a week's treatment, 14 entered