Considerable progress has been made in the induction therapy of acute myeloid leukemia (AML); however, current therapeutic results are still unsatisfactory in those with relapsed disease. The purine nucleoside analogue cladribine (2-chlorodeoxyadenosine, 2-CdA) has been shown to be a safe and active agent in acute myeloid leukemia. Synergistic interaction between cladribine and cytarabine has been demonstrated in preclinical and clinical studies.