Objective To study the reversal effect of adriamycin (ADM) resistance in human breast cancer cell line MCF-7/ADM by realgar (REA) combined with β-elemene (β-ELE), two types of anticancer drugs. Methods The sensitivity to ADM of MCF-7/ADM cells was studied by MTT assay.The intracellular accumulation of ADM in MCF-7/ADM cells was observed by fluorescentspectrophotometry. Expressions of P-GP protein and Bcl-2 protein were detected by flow cytometry. Results The combined treatment of REA and β-ELE could significantly enhance the cytotoxic effect of ADM on MCF-7/ADM cells to 4.2 fold as compared with the treatment of REA or β-ELE respectively (P<0.01). The intracellular accumulation of ADM in MCF-7/ADM cells was significantly increased after the combined treatment (P<0.01). The expression of P-GP protein in MCF-7/ADM cells was reduced from(95.90±3.02)% to (76.50±5.16)%(P<0.01) while the expression of Bcl-2 protein was reduced from(90.20±3.99)% to (50.00±1.63)%(P<0.01).Conclusion The combined treatment of REA and β-ELE could reverse more strongly the drug resistance to A