Objective:To investigate the expression of metastatic suppressor Kangai 1(KAI1) expression in the primary gallbladder carcinoma and its clinical significance.Methods: The clinical stages of 35 primary gallbladder carcinoma patients were determined according to the TNM criteria of International Union Against Cancer(UICC).Histopathologic changes and the expressions of KAI1 were detected by H-E and immunohistochemical methods,respectively.All the patients were followed up for 3 years.Results: It was found that 1 patient had carcinoma in situ(0 stage),13 had early carcinoma(Ⅰ-Ⅱ stage),and 21 had intermediate or advanced carcinoma(Ⅲ-Ⅳ stage).Histopathologic grading showed that 14 patients had well-differentiated carcinomas,10 had moderately differentiated ones,and 11 had poorly differentiated ones.Immunohistochemical results revealed that 60.00%(21/35) of the patients were positive of KAI1,with the positive rate being 92.31%(12/13) in early carcinoma(Ⅰ-Ⅱ stage) and 42.86%(9/21) in intermediate and advanced carcinoma(Ⅲ-Ⅳ stage),and the former was significantly higher than the latter(P_(exact)=0.00 476).The positive rate of KAI1 protein was negatively correlated with the clinical staging of patients(P_(trend)=0.004) and positively correlated with histopathologic grading(P_(trend)=0.001).The positive rate of KAI1 protein in well differentiated carcinoma was 92.86%(13/14),in moderately differentiated carcinoma was 60.00%(6/10),and in poorly differentiated carcinoma was 18.18%(2/11)(P_(exact)=0.000 475 between the 3 groups).The positive rate of KAI1 protein was 89.47%(17/19) in 19 survival patients and 25.00%(4/16) in 16 death cases.Obvious significance of the expression of KAI1 protein was found between the 2 groups(P=0.001).Conclusion: The positive rate of KAI1 is negatively correlated with the clinical staging but positively correlated with the histopathologic grading in patients with primary gallbladder carcinoma.The high expression of KAI1 genes may indicate a better prognosis of gallbladder carcinoma.