Objective: To investigate the correlation between CD4+CD25+ and CD4+CD25+Foxp3+ regulatory T cells (Treg) and transforming growth factor-β1 （TGF-β1） in peripheral blood of patients with epithelial ovarian cancer. Methods: The percentages of CD4+CD25+ and CD4+CD25+Foxp3+ Treg in peripheral blood from 24 patients with ovarian cancer were detected by flow cytometry. Plasma level of TGF-β1 in each patient was detected by enzyme-linked immunosorbent assay （ELISA）， and compared with that in 20 patients with benign ovarian tumor and 20 healthy volunteers. Results: The percentages of CD4+CD25+， CD4+CD25+Foxp3+ Treg cells and TGF-β1 in ovarian cancer patients were significantly higher than those in 20 patients with benign ovarian tumor and 20 healthy volunteers （both P<0.01）. Levels of CD4+CD25+， CD4+CD25+Foxp3+ Treg cells and TGF-β1 in ovarian cancer patients at stage Ⅲ~Ⅳ were significantly higher than those of patients at stage Ⅰ~Ⅱ（P<0.05）. Pearson correlation analysis showed that the percentages of CD4+CD25+ and CD4+CD25+Foxp3+ Treg cells were positively correlated with the levels of TGF-β1. Conclusion: The percentages of CD4+ Treg cells in peripheral blood from ovarian cancer were higher and positively correlated with TGF-β1 levels. Detection of CD4+ Treg cells and TGF-β1 has the clinical value on evaluation of development and prognosis of different stages of ovarian cancer. The increased levels of TGF-β1 may be involved in the immune negative adjustment mechanism of CD4+ Treg cells.