OBJECTIVE: MicroRNA-1294 (miR-1294) was reported to act as a tumor suppressor in several cancers. However, the biological function of miR-1294 in osteosarcoma (OS) has not been investigated. We, therefore, investigated the clinical significance and underlying mechanisms of miR-1294 in OS. PATIENTS AND METHODS: Quantitative Real-Time-Polymerase Chain Reaction (qRT-PCR) was conducted to detect the levels of miR-1294. Targets of miR-1294 were validated by luciferase reporter assay and Western blot. In vitro functional assays were performed to investigate the effects of miR-217 on cell proliferation and invasion. RESULTS: We found miR-1294 was downregulated in OS tissues and cell lines. Downregulation of miR-1294 has a significant negative impact on the overall survival of OS patients. Overexpression of miR-1294 suppresses OS cell proliferation and invasion in vitro. Then, luciferase reporter assay validated Homeobox A9 (HOXA9) was a downstream target of miR-1294. Expression patterns of miR-1294 were inversely correlated with HOXA9 in OS tissues, strengthening the findings from the luciferase reporter assay. Further functional assays revealed that overexpression of HOXA9 could reverse the inhibition effects of miR-1294 on cell proliferation and invasion. CONCLUSIONS: These results suggested miR-1294 functions as a tumor suppressor in OS progression by targeting HOXA9.