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Cadmium is a common environmental pollutant that causes bone damage. However, the effects of cadmium on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs) and its mechanism of action in this process are unclear. Here, we determined the effects of cadmium chloride (CdCl₂) on the osteogenic differentiation of BMMSCs and the potential mechanism involved in this process. As determined in the present investigation, CdCl₂, in a concentration-dependent manner, affected the viability of BMMSCs and their cytoskeletons. Exposure to 0.1 or 0.2 &#181;M CdCl₂ inhibited osteogenic differentiation of BMMSCs, which was reflected in the down-regulation of osteoblast-related genes (<i>ALP</i>, <i>OCN</i>, <i>Runx2</i>, <i>OSX</i>, and <i>OPN</i>); in suppression of the protein expression of alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2); and in decreased ALP activity and capacity for mineralization. Moreover, mRNA microarray was performed to determine the roles of these factors in BMMSCs treated with CdCl₂ in comparison to control BMMSCs. As determined with the microarrays, the Wingless-type (Wnt), mothers against decapentaplegic and the C. elegans gene Sam (SMAD), and Janus kinase-Signal Transducers and Activators of Transcription (JAK-STAT) signaling pathways were involved in the effects caused by CdCl₂. Moreover, during differentiation, the protein levels of Wnt3a, &#946;-catenin, lymphoid enhancer factor 1 (LEF1), and T-cell factor 1 (TCF1) were reduced by CdCl₂. The current research shows that CdCl₂ suppresses the osteogenesis of BMMSCs via inhibiting the Wnt/&#946;-catenin pathway. The results establish a previously unknown mechanism for bone injury induced by CdCl₂.