In order to test the toxicity and efficacy of intensive postremission therapy with high-dose cytosine arabinoside with L-asparaginase and amsacrine with etoposide in adults with acute nonlymphocytic leukemia (ANL), 100 adults (ages 19 to 75) with previously untreated ANL were entered into a study using six sequential cycles of chemotherapy. Cycles 1 (induction), 3, and 5 included conventional doses of daunomycin, cytosine arabinoside, 6-thioguanine, vincristine (VCR), and prednisone. Cycle 2 was cytosine arabinoside 3 g/m2 intravenously (IV) every 12 hours for four doses, followed by L-asparaginase 10,000 U intramuscularly (IM) at hour 42; this combination was repeated 1 week later. Cycle 4 included amsacrine 120 mg/m2/d and etoposide 100 mg/m2/d, both IV for five days, and cycle 6 was three monthly courses of VCR on day 1, and prednisone, mercaptopurine, and methotrexate each for five days. Seventy-four patients (74%) achieved complete remission (CR) (51 with cycle 1 and 23 after cycle 2). The overall disease-free survival (DFS) for patients achieving CR is 27% at 3 years by Kaplan-Meier analysis, while for patients achieving CR with cycle 1 it is 34%. The actuarial probability of being free from relapse at 3 years for patients achieving CR is 34%. Sixteen of the 74 CR patients (22%) died in CR while continuing to receive intensive chemotherapy, including 12 (18%) who succumbed to infection (nine bacterial, three fungal). After a median follow-up of 20 months, 36 patients have relapsed and 21 remain alive in CR. Intensive consolidation with high-dose cytosine arabinoside, amsacrine, and etoposide can modestly prolong DFS compared with historical controls. However, relapse continued to be a major problem and, in addition, with more aggressive consolidation therapy, infection during marrow aplasia resulted in a significant number of deaths.