BACKGROUND: Although deferasirox (DFX) is reported to have anti-tumor effects, its anti-leukemic activity remains unclear. We evaluated the effect of DFX treatment on two murine lymphoid leukemia cell lines, and clarified the mechanisms underlying its potential anti-leukemic activity. METHODS: L1210 and A20 murine lymphoid leukemia cell lines were treated with DFX. Cell viability and apoptosis were evaluated by the 3-(4,5-dimethylthaizol-2-yl)-5-(3-carboxymethylphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and fluorescence-activated cell sorting (FACS) analysis, respectively. Immunoblotting was performed to detect the expression of key apoptotic proteins. RESULTS: In dose- and time-dependent manner, DFX decreased viability and increased apoptosis of murine leukemic cells. Fas expression was significantly higher in A20 cells than in L1210 cells at all DFX concentrations tested. Although both cell lines exhibited high caspase 3 and caspase 9 expression, a critical component of the intrinsic mitochondrial apoptotic pathway, expression was greater in L1210 cells. In contrast, caspase 8, a key factor in the extrinsic apoptotic pathway, showed greater expression in A20 cells. Cytochrome c expression was significantly higher in L1210 cells. In both cell lines, co-treatment with ferric chloride and DFX diminished the expression of these intracellular proteins, as compared to DFX treatment alone. CONCLUSION: Treatment with DFX increased caspase-dependent apoptosis in two murine lymphoid leukemia cell lines, with differing apoptotic mechanisms in each cell line.