Background: The aim of this study is to determine the prognostic values of PDL1 expression in ovarian epithelial tumors and to detect the presence of FOXP3-positive T reg cells in the tumor microenvironment. Methods: This study included patients with benign, borderline or malignant ovarian serous tumors (n=82), mucinous cancer (n=17) and endometrioid cancer (n=36). FOXP3 and PDL1 were immunohistochemically evaluated and compared with histopathological and clinical prognostic parameters. Results: There was no expression of PDL1 in any tumor cell. However, PDL1-positive inflammatory cells were seen in 10 cases (7.3%) with mucinous carcinoma (n=6), endometrioid carcinoma (n=2), borderline (n=1), and benign (n=1) serous tumors. It was also determined that there was a significant positive correlation between PD-L1 expression in tumor infiltrating cells and survival (P<0.01). In 47 (34.3%) cases, there were FOXP3-positive cells. The number of FOXP3-positive cells was significantly higher in ovarian cancer, especially in serous and endometrioid carcinomas, rather than benign and borderline tumors (P=0.007). But there was no statistically significant association between the survival times and the presence of T regs (P=0.241). Conclusions: This study demonstrated that the presence of FOXP3 and PDL1-positive regulatory T cells in TILs was associated with mainly malignant tumors. We also found that the presence of PD-L1-positive inflammatory cells has a positive effect on survival.