High-dose, continuous infusion of intravenous mercaptopurine (HD 6MP) followed by intermediate-dose continuous cytarabine (ID Ara-C) has been shown to produce remissions in children with relapsed acute myeloid leukemia (AML). The purpose of this pilot study was to explore the feasibility of using this drug regimen as a component of treatment during the first remission of AML. Of 17 children with newly diagnosed AML registered in the study, 14 developed complete remission on conventional induction therapy and subsequently received the HD 6MP and ID Ara-C combination. The dosages of HD 6MP were escalated from 500 mg/m2 to 1250 mg/m2 in 24-hr infusions. The initial dosages of ID Ara-C were escalated from 250 mg/m2 to 650 mg/m2/24 hr and from 1 day to 4 days. Conventional treatment for AML was administered simultaneously. Seven of the 14 children remain in initial complete remission for 15 to 46 months and have completed treatment. Severe pancytopenia was observed in all patients, but there were no toxic deaths and no deaths during remission. The inclusion of HD 6MP and ID Ara-C in the treatment of AML in first remission appears to be feasible. Evaluation of its efficacy will require a comparative clinical trial.