Abstract: Objective To test the expressions of multiple drug resistance (MDR) gene of human gastric carcinoma, and investigate its significance in guiding gastric carcinoma clinical chemotherapy by choosing appropriate remedy according to examination result. Methods Eighty gastric cancer patients diagnosed by endoscopy and pathology were random divided into two groups (fit group and non-fit group),each included 40 patients. The expression of P-gp、GST-π、Topo-Ⅱ was tested in 80 gastric cancer specimen using immunohistochemistry. The fit group patients were treated by choosing sensitive chemical remedy fitting for gene examination result.The non-fit group patients were treated with the experiential chemotherapeutic scheme of FOLFOX4. Results Positive expression rates of P-gp、GST-π、Topo-Ⅱ in 80 cases of gastric cancer were 51.5%、57.5%、46.3%,respectively. There were some correlations between the positive expression of P-gp、Topo-Ⅱ and the degree of tumor differentiation,which was higher in well differentiated tumor than that in poor differentiated one for P-gp,but it was reverse for Topo-Ⅱ. There were no correlations between the positive expression of GST-π and the degree of tumor differentiation. The response rate was 57.5% in the fit group,which was 35% in the non-fit group. There were significant different between the two groups (P<0.05). Conclusion The mechanisms of drug resistance of P-gp、GST-π、Topo-Ⅱ in gastric cancer are different.It is of significance for guiding gastric cancer clinical therapy by applying the different,sensitive,scientific individual chemotherapy according to the detection results of drug resistance gene, and is helpful to achieve better chemotherapy efficacy for gastric cancer patients.