Seventeen elderly patients with acute nonlymphocytic leukemia (EP-ANLL) were treated with cytarabine, either 1.5 g/m2 or 2.0 g/m2 q 12 h for 4 days [attenuated high-dose ARA-C (HDARAC)]. One complete and one partial response was seen in 15 evaluable cases. Toxicity, evaluated in all 17 patients, was severe, with 47% showing a variety of Eastern Cooperative Oncology Group grade 3, 4, or 5 toxicities. Forty-one percent of all patients died within 33 days of initiating treatment. We conclude that attenuated HDARAC is ineffective in inducing remission and is very toxic in the EP-ANLL.