In a phase I/II study the tolerable doses and antileukemic efficacy of the combination AMSA and etoposide (VP 16-213) was assessed in 20 patients with refractory acute myeloid leukemia. The following 5 day treatment course was found tolerable and effective: AMSA 210 mg/m2/die on days 2, 3 and 4, and etoposide on days 1 and 5 as a 1 h infusion of 100 mg/m2 followed by a 23-h continuous infusion of 230 mg/m2. In 5 of 20 patients partial remissions were achieved; 4 of these patients were primarily resistant against two TAD induction cycles. Bone marrow aplasia without a residual blast population was achieved in 7 of the 8 patients with primary TAD resistance. AMSA/etoposide thus seems to express an antileukemic efficacy without cross-resistance against TAD.