Epithelial-mesenchymal transition (EMT) has been implicated in tumor invasion and metastasis and provides novel strategies for cancer therapy. Hypaconitine (HpA), a diester-diterpenoid alkaloid isolated from the root of the Aconitum species, exhibits anti-inflammatory, analgesic, and especially, cardiotoxic activities. Here, we reported the anti-metastatic potentials of HpA in transforming growth factor-beta 1 (TGF-beta 1)-induced EMT in lung cancer A549 cells. The cytotoxic effect of HpA was determined by MTT assay. A549 cells were treated with TGF-beta 1 with or without HpA co-treatment, and the morphological alterations were observed with a microscopy. The expression of E-cadherin, N-cadherin, and NF-kappa B was determined by both Western blotting and immunofluorescence analyses. The adhesion, migration, and invasion were detected with Matrigel, wound-healing, and transwell assays, respectively. The expression of Snail was determined by Western blotting. The expression of NF-kappa B p65, I kappa B alpha, and p-I kappa B alpha in nuclear and cytosolic extracts was assessed by Western blotting. The results showed that low concentration of HpA (< 16 mu mol.L-1) had no obvious cytotoxicity to A549 cells. Morphologically, TGF-beta 1 treatment induced spindle-shaped alteration in the cells. The upregulation of N-cadherin, NF-kappa B, and Snail and the downregulation of E-cadherin were detected after TGF-beta 1 treatment. The adhesion, migration and invasion abilities were also increased by TGF-beta 1. Besides, TGF-beta 1 induced expression of Snail in a time-dependent manner. Furthermore, TGF-beta 1 induced nuclear translocation of NF-kappa B p65. All these alterations were dramatically inhibited by HpA co-treatment. In addition, the NF-kappa B inhibitor PDTC showed similar inhibitory effect. In conclusion, these results showed that HpA inhibited TGF-beta 1-induced EMT in A549 cells, which was possibly mediated by the inactivation of the NF-kappa B signaling pathway, providing an evidence for anti-cancer effect of HpA.