['To investigate the effect of targeted antiosteosarcoma methotrexate-bisphosphonate conjugate on growth inhibition and apoptosis in human osteosarcoma MG-63 cells.', 'MG-63 cells were treated with various concentrations of methotrexate-bisphosphonate conjugate and apoptosis was monitored via an MTT assay, cell morphology, TUNEL assay and flow cytometry analysis.', 'The survival rate of MG-63 cells treated for 24 to 96 hours with 2000 mg/ml or more of methotrexate-bisphosphonate conjugate decreased significantly. Cells treated with conjugate showed typical apoptotic features using inverted phase contrast microscopy and fluorescence staining, and the majority of cells demonstrated a positive result in the TUNEL assay. Karyopyknosis and crescent aggregation of chromatin were observed in conjugate-treated cells by electron microscopy. Flow cytometry of MG-63 cells treated with methotrexate-bisphosphonate conjugate showed a time and dose-dependent increase in apoptosis (p < 0.05).'] Does targeted antiosteosarcoma methotrexate-bisphosphonate conjugate induce apoptosis of osteosarcoma cells in vitro?