Although HOX genes are best known for acting in the regulation of important events during embryogenesis, including proliferation, differentiation and migration, alterations in their expression patterns have been frequently described in cancers. In previous studies we analyzed the expression profile of the members of the HOX family of homeobox genes in oral samples of normal mucosa and squamous cell carcinoma (OSCC) and identified differently expressed genes such as HOXA10. The present study aimed to validate the increased expression of HOXA10 in OSCCs, and to investigate the effects arising from its knockdown in OSCC cells. The levels of HOXA10 mRNA were determined in human OSCC samples and cell lines by quantitative PCR, and HOXA10-mediated effects on proliferation, apoptosis, adhesion, epithelial-mesenchymal transition (EMT), migration and invasion were studied in HSC-3 tongue carcinoma cells by using retrovirus-mediated RNA interference. Higher expression of HOXA10 mRNA was observed in OSCC cell lines and in tumor tissues compared to normal controls. HOXA10 knockdown significantly reduced the proliferation of the tumor cells which was accompanied by increased levels of p21. HOXA10 silencing also significantly induced the expression of EMT markers and enhanced the adhesion, migration and invasion of HSC-3 cells. No effects on cell death were observed after HOXA10 knockdown. The results of the current study confirm the overexpression of HOXA10 in OSCCs, and further demonstrate that its expression is functionally associated with several important biological processes related to oral tumorigenesis, such as proliferation, migration and invasion.