Overexpression of the melanoma differentiation associated gene-7 (MDA-7)/IL-24 in vitro generally results in the growth suppression and induction of apoptosis of diverse human tumor cells. In this study, we investigated the effects of overexpression of the MDA-7/IL-24 gene in human hepatocellular carcinoma (HCC) cells in vitro and in vivo. Adenovirus-mediated overexpression of MDA-7 facilitated the MDA-7/IL-24-induced apoptosis and G(2)/M arrest in HCC cells, but not in the normal liver cell line L02, and the effect was independent of the p53 status. Inhibition of metastasis and angiogenesis was correlated with decreasing expression of STAT3, P-STAT3, MMP-2, VEGF, and TGF-beta genes, regulated by STAT3 in MHCCLM6 cells. We also showed that Ad.mda-7 combined with doxorubicin (ADM) had significantly enhanced antitumor and antimetastatic effects in vivo, accompanied by the downregulation of VEGF, MMP-2, and TGF-beta genes and the upregulation of E-cadherin genes. These data suggested that MDA-74L-24 induces its selective antitumor properties in HCC cells by promoting apoptosis independent of p53 status, inhibiting subcutaneous tumor growth and metastasis, and increasing the effect of chemotherapeutic agents. MDA-71IL-24 represents a new class of cancer suppressor genes that may be useful in the targeted therapy of HCC.