The epidermal differentiation complex (EDC) contains a large number of gene products which are crucialfor the maturation of the human epidermis and can contribute to skin diseases, even carcinogenesis. It isgenerally accepted that activation of oncogenes and/or inactivation of tumor suppressor genes play pivotalroles in the process of carcinogenesis. Here, NICE-3, a novel EDC gene, was found to be up-regulated in humanhepatocellular carcinoma (HCC) by quantitative real-time RT-PCR. Furthermore, overexpression of exogenousNICE-3 by recombinant plasmids could significantly promote cell proliferation, colony formation and soft agarcolony formation in Focus and WRL-68 HCC cell lines. Reversely, NICE-3 silencing by RNA interference couldmarkedly inhibit these malignant phenotypes in YY-8103 and MHCC-97H cells. Moreover, cell cycle analysis ofMHCC-97H transfected with siRNA by flow cytometry showed that NICE-3 knockdown may inhibit cell growthvia arrest in G0/G1 phase and hindering entry of cells into S phase. All data of our findings indicate that NICE-3may contribute to human hepatocellular carcinoma by promoting cell proliferation.