Objective:To investigate the possible role of microRNA-125b(miR-125b) in the development of multidrug resistance (MDR) in human gastric cancer cell line SGC7901/VCR. Methods:Using quantitative real-time PCR analysis and Western blot to detect the expression difference of miR-125b and anti-apoptotic protein BCL2 and MCL1 between multidrug-resistant human gastric cancer cell line SGC7901/vincristine(VCR) and its parental SGC7901 cell line, respectively. BCL2 and MCL1 3’-untranslated region-based luciferase reporter plasmids were constructed to testify the target genes of miR-125b. Transient transfection of miR-125b mimic was used to up-regulate the expression level of miR-125b in SGC7901/VCR cells and the effect of miR-125b on the expression of BCL2, MCL1 and the MDR phenotype was observed. Flow cytometry was used to detect VCR-induced apoptosis of the SGC7901/VCR cells after transfection. Results:miR-125b was low expressed in multidrug-resistant human gastric cancer cell line SGC7901/VCR, and the downregulation of miR-125b was concurrent with the overexpression of antiapoptotic genes BCL2, MCL1 in SGC7901/VCR cells compared with the parental SGC7901 cell line. The luciferase activity of BCL2 and MCL1 3’-untranslated region-based reporters constructed in SGC7901/VCR cells suggested that BCL2 and MCL1 were the common target genes of the miR-125b. Overexpression of miR-125b sensitized SGC7901/VCR cells to anticancer drugs of VCR, CDDP, ADR and VP-16. Overexpression of miR-125b also inhibited the expression of BCL2, MCL1 and sensitized SGC7901/VCR cells to VCR-induced apoptosis. Conclusion:miR-125b plays a role in the development of MDR in human gastric cancer cell line, at least in part, by modulation of apoptosis via targeting BCL2 and MCL1.