ABSTRACT. Dysregulation of microRNAs (miRs) is associated with cancer development and progression and aberrant expression of miR-874 have been found in some types of cancer. However, the expression and function of miR-874 in osteosarcoma remain unclear. The aim of this study was to explore the effects of miR-874 in osteosarcoma tumorigenesis and development. The expression level of miR-874 was quantified by real-time reverse transcription-polymerase chain reaction (RT-PCR) in human osteosarcoma cell lines and tissues. Using a miR-874 mimic, cell proliferation and migration assays were performed in an osteosarcoma cell line and tumorigenicity was observed in vivo in order to determine the effects of miR-874 in osteosarcoma cell lines and tissues. MiR-874 was significantly downregulated in osteosarcoma cell lines and clinical (2015) specimens. Decreased miR-874 expression was significantly associated with large tumor size, distant metastasis, and advanced clinical stage, and was an independent predictor of poor survival. Overexpression of miR-874 inhibited cell proliferation, invasion and migration in vitro, promoted cell apoptosis in vitro, and suppressed tumorigenicity in vivo. These findings indicate that miR-874 may act as a tumor suppressor in osteosarcoma and could serve as a novel therapeutic agent for miRbased therapy.