Thirty-three patients (22 men and 11 women; median age, 44 years) with newly diagnosed acute nonlymphocytic leukemia (ANLL) were treated with a combination of mitoxantrone, an anthracenedione derivative, 10 mg/m2/d for 3 days, plus cytosine arabinoside (ara-c), 100 mg/m2/d for 7 days. Patients not responding after two courses of therapy were considered treatment failures. Responding patients received two consolidation courses. Complete remission was achieved in 24 patients (73%) half of whom responded after a single course of therapy. Two patients were refractory and 7 died due to bone marrow depression. The median disease-free survival was 390 days, and the median overall survival was 450 days; 2 patients were still alive after 979 and 1166 days, respectively. Apart from hematologic findings, the most commonly observed toxicities were nausea/vomiting, alopecia, and infection. Mitoxantrone combined with ara-c is an effective and safe combination in the treatment of newly diagnosed ANLL.