Abstract: Objective:To investigate the expression and pathological features of carbonic anhydrase Ⅸ(CAⅨ)in the ovarian epithelial cancer,and to find out the role of anoxia in the genesis and progression of the disease.Methods:The expression of CAⅨ was determined by immunohistochemical staining in 40 cases of ovarian epithelial cancer,30 cases of carcinoma in situ and 30 cases of normal ovarian tissue.Results:The positive staining rate of CAⅨ in the normal tissue,the carcinoma in situ and ovarian epithelial cancers were 0.0%，16.7% and 52.5%,respectively;The difference was significant(P0.05).In ovarian epithelial cancers,the expression of CAⅨ was significantly associated with the surgical stage,differentiation and lymphatic invasion(P＜0.05).Conclusions:CAⅨ plays an important role in the genesis,invasion and metastasis of the ovarian epithelial cancer;high expression of CAⅨ may be one of the factors for poor prognosis of ovarian epithelial cancers.