Objective To explore the effect of miR-24-2 on the in vitro proliferation of U-2OS cells. Methods U-2OS cells were randomly allocat-ed into 4 groups:miR-24-2 mimic group,miR-24-2 inhibitor group,negative control group,and normal control group. MicroRNAs were transfected into U-2OS cells using Lipofectamine?2000. miR-24-2 expression level and the proliferation of U-2OS cells after transfection were detected by real-time quantitative RT-PCR(RT-qPCR)and MTT proliferation assays,respectively. Results RT-qPCR results showed that miR-24-2 level was sig-nificantly higher in the miR-24-2 mimic group and lower in the miR-24-2 inhibitor group than those in the controls,indicating the successive trans-fection. MTT proliferation assay results proved that the cell viability was significantly lower in the U-2OS cells transfected with miR-24-2 mimic and higher in inhibitor groups compared to the control. Conclusion MiR-24-2 inhibits growth of the U-2OS cells,which could be a potential biomarker in the treatment of osteosarcoma.