Abstract: Objective To evaluate the methylation status of CpG islands in WWOX gene promoter region of epithelial ovarian cancer,and to explore the relationship between methylation state of WWOX gene CpG island and clinicopathological indexes in epithelial ovarian cancer. Methods The methylation state of WWOX gene CpG island was evaluated by methylation specific polymerase chain reaction(MSP) in 48 patients with epithelial ovarian cancer,18 patients with borderline epithelial ovarian tumors,26 patients with epithelial benign tumors,and 33 patients with normal ovarian tissues. Results The rates of CpG island methylation in WWOX gene promoter region in epithelial ovarian cancer tissues,borderline ovarian tumor tissues and benign ovarian tumor tissues were 43.75%,26.32% and 3.84%,respectively.Normal ovarian tissues were completely unmethylated in WWOX gene CpG island.The rate of CpG island methylation in epithelial ovarian cancer tissues was higher than that in other ovarian tissues,and these differences were found to be statistically significant (P<0.01).The rate of CpG island methylation in WWOX gene promoter region in late-stage (stageⅢ,Ⅳ) epithelial ovarian cancer tissues was higher than that in early-stage (stageⅠ,Ⅱ) epithelial ovarian cancer tissues,and these differences were found to be statistically significant (P<0.05). Conclusion Epithelial ovarian cancer tissues show widespread CpG island methylation in WWOX gene promoter region,which may be explained as the important mechanism that leads to WWOX gene inactivation.A typical methylation of WWOX gene is germane to generation and progression of epithelial ovarian cancer,which makes it probably be an important indicator in epithelial ovarian cancer early diagnosis and prognosis evaluation.