Abstract: Objective 　To investigate the effect of neferine (Nef ) on the proliferation, intracellular ADM concent ration and the expression of mdr-1/P-gp in human breast cancer cell line MCF-7/ Adr. Methods 　MTT method was used to observe cell proliferation. High performance liquid chromatography was used to detect int racellular ADM concent ration. RT-PCR and Western-blotting were used to detect mdr-1/P-gp expression. Results 　The inhibiting rate and int racellular ADM concent ration of 10μg/ ml Nef adding ADM group were significantly higher than those of ADM group ( P < 0. 01) . The inhibiting rate and intracellular ADM concent ration of 20μg/ ml Nef adding ADM group were significantly higher than those of 5μg/ ml verapamil adding ADM group and 10μg/ ml Nef adding ADM group ( P < 0. 01) . The mdr-1 mRNA and P-gp expression of 10μg/ml Nef adding ADM group was significantly lower than those of 60μg/ml ADM group ( P < 0. 01) . The mdr-1 mRNA and P-gp expression of 20μg/ml Nef adding ADM was significantly lower than that of 10μg/ml Nef adding ADM group group ( P < 0. 01) . Conclusion 　Neferine can inhibit the proliferation of human breast cancer cell line MCF-7/Adr. Neferine can improve the int racellular ADM concent ration. Neferine can reduce mdr-1 mRNA and P-gp expression and consequently reverse MDR.