BACKGROUND: Although there are multiple treatments for lung cancer, the death rate of this cancer remains high because of metastasis in earlier stages. So a novel treatment for overcoming metastasis is urgently needed. Overexpression of high-mobility group AT-hook 2 (HMGA2), a nonhistone chromosomal protein has been observed in metastatic cancers. So, we suggested that HMGA2 upregulation may play a critical role in treating lung cancer. METHODS: The A549 cells were transfected with specific HMGA2 small interfering RNA (siRNA) using transfection reagent. Relative HMGA2 and matrix metallopeptidase 1 (MMP1), C-X-C chemokine receptor type 4 (CXCR4), vimentin, and E-cadherin messenger RNA expression levels were measured by quantitative real-time polymerase chain reaction. To diagnose cytotoxic effect of HMGA2 siRNA and other components of transfection process, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was applied. The migration capacity after transfection with HMGA2 siRNA was detected by wound-healing assay. RESULTS: HMGA2 siRNA significantly reduced HMGA2 expression in a dose-dependent manner 48 hours after transfection. Expression levels of MMP1, vimentin, and CXCR4 were reduced, but E-cadherin level was not changed meaningfully. HMGA2 knockdown significantly reduced cell survival rate and also led to the inhibition of cell migration. CONCLUSIONS: Our results indicated that RNA interference by downregulation of HMGA2 gene expression and affecting downstream genes led to the inhibition of cell migration and proliferation. Therefore, HMGA2 siRNA might be an alternative treatment option for metastatic lung cancer.