To evaluate the expression of tumor suppressor gene phosphatase and tensin homologue on chromosome 10 (PTEN) in ovarian epithelial tumors and its correlation with tumor growth and clinicopathologic features in ovarian adenocarcinomas.Immunohistochemical staining with anti-PTEN antibody was performed in 54 adenocarcinomas and 23 borderline tumors of the ovary. The apoptotic cells were visualized by terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling, and proliferative cells were visualized by staining with Ki-67 antibody.Reduced PTEN expression was significantly higher among the adenocarcinomas than the borderline tumors (p < 0.001). Reduced PTEN expression in adenocarcinomas did not correlate with International Federation of Obstetrics and Gynecology (FIGO) stage. The Ki-67 index (KI) and apoptotic index were significantly higher in adenocarcinomas as compared with borderline tumors (p < 0.001). Tumors with reduced PTEN expression in ovarian adenocarcinomas had a significantly higher KI than those with normal PTEN expression (p < 0.01). By univariate analysis, FIGO stage and histologic type correlated with survival. However, FIGO stage was the only independent prognostic factor by multivariate analysis.Our results suggest that alteration of the PTEN gene may be associated with malignant transformation of ovarian epithelial tumors. The PTEN gene seems to be a negative regulator of cell proliferation in ovarian adenocarcinomas.