SCOPE: Short-chain fatty acid sodium butyrate (NaB) is the byproduct of bacterial anaerobic fermentation of dietary fiber in the colon, and has been shown to have an antitumor effect on colorectal cancer (CRC). The miR-200 family is a key regulator of the epithelial-mesenchymal transition (EMT). We investigate the role of miR-200s expression on cell migration in NaB-treated CRC cells. METHODS AND RESULTS: HCT116 and LOVO CRC cells treated with NaB depicted reduced cell proliferation, enhanced apoptosis, and cell cycle arrest. NaB inhibited cell migration in the wound healing and transwell assays, and in spheriod cultures while regulating EMT-related protein expression. NaB reciprocally increased miR-200s but reduced expression of their target genes (Bmi-1, Zeb1, EZH2). Cells transfected with miR-200c shRNA displayed a significant blockade of NaB-induced anti-invasive activity. Upregulation of Bmi-1 expression partially reversed the effect of NaB. In addition to inhibition of tumor growth in vivo, qRT-PCR results showed that NaB increased miR-200c/200b/492 expression in the tumor tissues. Immunohistochemistry and Western blotting results demonstrated that NaB decreased Bmi-1 expression in vivo. CONCLUSION: NaB inhibits CRC cell migration by enhancing miR-200c expression-mediated downregulation of Bmi-1. These findings support the utility of NaB in colorectal cancer therapy.