['To study and characterize the potential antitumoral effects of zoledronic acid (ZA) on renal cancer cell lines in vitro.', 'Three different and well-characterized renal cancer cell lines were studied, namely ACHN, A-498 and CAKI-2. The cytotoxic potential of ZA was evaluated using a fluorometric microculture cytotoxic assay. The degree of M30 induction following ZA treatment was measured using an M30 enzyme-linked immunosorbent assay (ELISA), and the blockage of this effect was studied using a pan-caspase inhibitor. Immunofluorescence of the M30 neoepitope was performed to visualize the M30-inducing properties of ZA.', 'A significant reduction in viable cells was seen for all three cell lines following treatment with ZA, compared with untreated controls. This effect was most pronounced for the ACHN cells, as only 4% were viable following incubation with ZA for 72 h. A concomitant increase in the apoptosis significant caspase-dependent M30 antigen was demonstrated. This effect could be blocked by the pan-caspase inhibitor Z-VAD.'] Does zoledronic acid induce caspase-dependent apoptosis in renal cancer cell lines?