We investigated the association between peroxiredoxin III (PRX III) and chemotherapy resistance in ovarian cancer. Patient's specimens were taken at the time of surgery. Determination of resistance is based on whether first diagnosis of relapse occurred within 6 months after the cessation of chemotherapy. PRX III expression was immunohistochemically determined in paraffin-embedded specimens from platinum-resistant (Pt-resistant) and platinum-sensitive (Pt-sensitive) patients. The Pt-resistant group had significantly higher PRX III protein compared to the Pt-sensitive group. The two groups showed no significant differences in pathological classification and age, although they differed significantly in tissue differentiation and stage. PRX III protein was significantly higher in the Pt-resistant serous carcinomas, in moderately and poorly differentiated, and in stage III and IV ovarian cancer tissues compared to the Pt-sensitive group. PRX III may be associated with drug resistance in ovarian cancer.