INTRODUCTION: Ovarian cancer is generally diagnosed at advanced stages of the disease; therefore, poor prognoses are typical. The development of tumor markers is thus of utmost importance. Prostasin is a protease that in normal tissues is highly expressed only in the prostate gland and seminal fluid. A previous study showed that prostasin is highly overexpressed in ovarian cancer cell lines. This study sought to evaluate the expression of prostasin in ovarian cancer. METHODS: Fresh tumor samples of ovarian epithelial cancer (n: 12) were analyzed for expression of prostasin mRNA (messenger ribonucleic acid) by conventional and real time quantitative PCR (polymerase chain reaction). As a standard control, a normal prostate sample was analyzed. RESULTS: Using conventional PCR, prostasin was detected in all but one sample. Using quantitative PCR, prostasin was over-expressed in all but one of the samples as compared to the control (prostate). CONCLUSIONS: These findings indicate that prostasin is overexpressed in many epithelial ovarian cancers. Further studies of prostasin as a potential biomarker for this disease are warranted.