In light of the poor prognosis for ovarian cancer patients, the research continues for innovative and efficacious treatment modalities. Along with surgical and chemotherapeutic regimens, gene therapy has emerged as one of the leading contenders in the treatment armamentarium. Hepsin is a type II transmembrane serine protease originally identified in the human liver as a cDNA clone. However, the biological function of Hepsin expression remains unclear. Apoptotic cell was increasingly common among higher proportions of Hepsin transfectants. We discovered that first-time stable transfectants of Hepsin significantly inhibited cell growth in the monolayer, anchorage-independent cell growth in the soft agar in vitro, and tumorigenicity in vivo in ovarian cancer cell lines. These results demonstrated that Hepsin has a potential therapeutic effect that inhibits through up-regulation of p53-dependent apoptosis and caspase-3, -6, and -7 activations. Our findings in this study identify Hepsin as a target for new approaches in ovarian cancer treatment.