Résumé : One hundred and nine consecutive patients with de novo acute nonlymphocytic leukemia aged over 56 years were admitted with the intention of administering high-dose cytosine arabinoside (HD Ara-C) intensification. After remission induction, the patients were consolidated with a course of daunorubicin (30 mg/m2/day, days 1-3) and Ara-C (100 mg/m2/day, days 1-7), followed by the intensification (Ara-C, 2 g/m2/12 h, days 1-4). The planned induction course was not started in 13 patients because of cardiac failure or unsatisfactory general status. Remission was achieved in 55% (53/96) of the patients. Twenty-seven patients (28%) had refractory disease, seven died early during induction therapy, five died of hemorrhage and three of infection during the hypoplasia that followed induction treatment. Thirty-nine patients started consolidation and 32 had the planned intensification. In these last patients the 3-year leukemia-free survival (LFS) probability was 29% (SE, 8%). No patient died as a consequence of intensification. The relapse rate of the intensified patients did not differ from the relapse rate of those patients who did not receive the planned intensification (p = 0.12). The only pretreatment variables significantly associated with a better LFS were younger age (p = 0.02) and a low WBC at diagnosis (p = 0.04). For the whole patient group, the 3-year survival probability was 15% (SE, 4%). This study shows that elderly patients can tolerate HD Ara-C. The patients completing consolidation-intensification have a currently acceptable LFS. To what extent HD Ara-C contributed to the length of the remissions remains unclear.