Backgroud and Aims: MicroRNA-206 has proven to be down-regulated in many human malignancies in correlation with tumour progression. Our study aimed to characterize miR-206 contributions to initiation and malignant progression of human osteosarcoma. Methods: MiR-206 expression was detected in human osteosarcoma cell 1ine MG63, human normal osteoblastic cell line hFOB 1.19, and paired osteosarcoma and normal adjacent tissues from 65 patients using quantitative RT-PCR. Relationships of miR-206 levels to clinicopathological characteristics were also investigated. Moreover, miR-206 mimics and negative control siRNA were transfected into MG63 cells to observe effects on cell viability, apoptosis, invasion and migration. Results: We found that miR-206 was down-regulated in the osteosarcoma cell line MG63 and primary tumor samples, and decreased miR-206 expression was significantly associated with advanced clinical stage, T classification, metastasis and poor histological differentiation. Additionally, transfection of miR-206 mimics could reduce MG-63 cell viability, promote cell apoptosis, and inhibit cell invasion and migration. Conclusions: These findings indicate that miR-206 may have a key role in osteosarcoma pathogenesis and development. It could serve as a useful biomarker for prediction of osteosarcoma progression, and provide a potential target for gene therapy.