Abstract: Objective To investigate the expression of transmembrane 4 super family 1（TM4SF1） protein in human ovarian tissues and its relationship with clinicopathological factors. Methods The SP immunohistochemical method was used to analyze the expression of TM4SF1 protein in 16 normal ovarian epithelial tissues， 23 benign ovarian tumor tissues and 55 epithelial ovarian cancer （EOC） tissues.Relationships of TM4SF1 expression with clinicopathological features of EOC and patient prognosis were analyzed. Result ①EOC tissues showed a significantly higher rate of TM4SF1 protein expression（90.90%）than did benign ovarian tumor tissues（65.22%）or normal ovarian epithelial tissues（25.00%，P<0.05）.②The TM4SF1 protein showed markedly different localizations in various tissue types. In normal ovarian epithelial tissues，the protein localized primarily to the membranes and the basal surface of epithelial cells as well as cytoplasts; in benign ovarian tumors， the protein was observed mainly on the basal surface and in certain parts of tumor cell membranes；in EOC tissues，TM4SF1 showed a mainly cytoplasmic staining.③ Rate of TM4SF1 protein expression was significantly higher in tissues of patients with stage Ⅲ-Ⅳ EOC than in patients with stage Ⅰ-Ⅱ disease（P<0.05）.The rate of TM4SF1 protein expression was also significantly higher in tissues showing low-to intermediate tumor differentiation than in well-differentiated carcinoma tissues（P<0.05）.④ Rate of TM4SF1 protein expression showed no significant association with histological type or amount of ascites （P>0.05），but association with FIGO stage and histological grade（P＜0.05）.⑤ Cox multivariate analysis showed that positive expression of TM4SF1 protein was not an independent prognostic factor. Conclusion TM4SF1 protein is overexpressed in EOC tissue，so it may be associated with the disease.

Key words: Ovarian neoplasm, TM4SF1, Epithelial ovarian cancer, Immunohistochemistry