A pilot study was conducted to determine the possible efficacy and the toxicities associated with the administration of four courses of intensive consolidation chemotherapy to patients with acute nonlymphocytic leukemia in remission. All therapy was completed within 6 months. The median duration of remission was 22 months, with 45+% of patients in remission at 3 years and few relapses to date thereafter. Sixty percent of patients experienced significant side effects after each course of therapy. The therapy appeared to be particularly efficacious for patients less than 45 years of age, since 65% are alive at 3 years and there is no projection for a median duration of remission as yet. The cytogenetic characteristics of the leukemic cells, the percentage of S phase cells, and the height of the WBC count were the most important prognostic characteristics at diagnosis.