69 patients (median age 53 years, 19–79 years old) with untreated acute non-lymphoblastic leukemia (ANLL) were randomized to receive either a regimen of amsacrine, cytarabine, thioguanine (AAT) or daunorubicine. cytarabine, thioguanine (DAT). AAT consisted of amsacrine 200 mg/m2/day × 5, thioguanine 100 mg/m2/12 h p.o. × 10; DAT was daunorubicine 50 mg/m2/day × 3, cytarabine 200 mg/m2/day × 5, thioguanine 100 mg/m2/12 h p.o. × 10. After one or two induction courses the patients subsequently received 2 consolidation courses. 17 patients were not assessable for response to therapy due to exitus during induction treatment. Complete remission could be obtained in 14/24 (58%) of DAT patients respectively. Patients < óO years of age achieved CR in 63% (AAT) vs 65% (DAT), whereas patients ≥60 years obtained a CR in 50% (AAT) vs 13% (DAT). Toxicity appears not to be increased significantly with amsacrine. These data indicate that amsacrine could replace daunorubicine in remission induction regimens of ANLL containing cytosin arabinoside and thioguanine without decreasing the resp