Thirteen patients with leukemia were treated with a combination of cytosine arabinoside (ara-C) (3 g/m2 by 1-h infusion every 12 h for 12 doses) and etoposide (100 mg/m2 daily over 1 h for 3 doses). Toxicity of the regimen consisted of severe hematologic suppression, moderate abdominal colic with vomiting and diarrhea, and occasionally severe central nervous system (CNS) toxicity. Two patients received the regimen as consolidation for acute myelogenous leukemia in remission. Of the remaining 11 patients with chronic myeloid leukemia (CML)-blast crises or relapsed/refractory acute myeloid leukemia (AML), nine patients (82%) obtained CR (or chronic phase) and two patients obtained partial remission (PR). High-dose ara-C and etoposide is an effective but toxic regiment for the treatment of relapsed or refractory myeloid leukemias.