Abstract: Objective To explore the mechanism of multi-drug resistance(MDR)in the human gastric carcinoma MDR subline SGC7901/VCR.Methods The density of vincristine(VCR)was increased gradually to induce the drug resistance of gastric carcinoma cell SGC7901.MTT assay was used to determine the lethal effect of anticarcinogens on tumor cells and Western blot assay was applied to determine the expression of P-gp and GST-s in tumor cells.Results The resistance of SGC7901/VCR cells to VCR, fluorouacil, and epirubicin were 16.56, 2.69 and 13.05 times, respectively, more than that of SGC7901 cells.Expressions of P-gp and GST-s in resting SGC7901/VCR cells were significantly higher than that in carcinogen-sensitive SGC7901 cells.Conclusion The density of vincristine(VCR)was increased gradually to induce the drug resistance of gastric carcinoma cell SGC7901.Expression of P-gp and GST-s in resting SGC7901/VCR cells was significantly more than that in carcinogen-sensitive SGC7901 cells.On the contrary, Inhibiton of P-gp and GST-s may reverse drug resistance of SGC7901/VCR cells.