Objective To analyse the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in ovarian epithelial cancer and to investigate the relationship between PTEN and clinical pathology and prognosis of ovarian epithelial cancer.Methods Expression of PTEN in 10 normal ovarian tissues,20 benign tumors and 60 cases of ovarian epithelial cancers were detected by immunohistochemical method.Results The positive expression of PTEN in normal ovarian and benign tumor tissues were significantly higher than that in ovarian epithelial cancers (100％ (10/10) vs 80.0％ (16/20) vs 53.3％ (32/60),x2 =7.778 and 4.444 respectively,P ＜ 0.05).The expression of PTEN was correlated to clinical stage,histilogical grade,presence and metastasis of lymph node (x2 =4.339;6.465 ;3.896;10.452;P ＜0.01),but there was no correlation to age,histological type and ascites (x2 =0.004 ;0.388 ; 1.057 ; P ＞ 0.05).Conclusion The expression of PTEN is related to ovarian carcinogenesis and development and may has great value in clinical diagnosis and prognosis of ovarian carcinogenesis.