Abstract: Objective :To investigate the expression of Bmi-1 (B cell-specific MLV integrationsite-1) and its clinicopathologic significance in gastric cancer. Methods : The expression of Bmi-1 mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR) in cancer samplesand adjacent non-cancerous samples from 20 gastric cancer patients.The expression of Bmi-1 proteinwas examined by immunohistochemistry in archival paraffin-embedded tissue specimens. Statisticalanalysis was performed to investigate the association between the clinicopathologic features and Bmi-1expression. Results :RT-PCR demonstrated that the levels of Bmi-1 mRNA in gastric cancer sampleswere significantly higher than those in adjacent non-cancerous tissues. Immunohistochemical stainingshowed that Bmi-1 was moderately or highly expressed in 67.8%(99/146) of gastric cancer. Expressionof Bmi-1 was highly correlated with tumor size, clinical stage, lymph node metastasis and T classifica-tion(P<0.05).On the other hand, it was not correlated with gender,age,or tumor differentiation(P>0.05). Conclusion :Overexpression of Bmi-1 in gastric carcinoma enhances invasion and metastasis. Bmi-1may serve as a good prognostic factor to indicate biologic behavior of gastric carcinoma.