Abstract: Objective To investigate the molecular mechanism of ABCC4 gene in the recurrence of drug resistance in gastric cancer. Methods ABCC4 expression in gastric cancer tissue and multi-drug resistant gastric cancer cells were detected by immunohistochemistry, Western blot, RT-PCR and flow cytometry. The expression level of ABCC4 was down-regulated by RNA interference in drug-resistant gastric cancer cells. Results ABCC4 was highly expressed in variety of cancer cells, especially in drug-resistant gastric cancer cells, however, it was lowly or deficiently expressed in normal gastric mucosa cells. Down-regulating ABCC4 by RNA interference could lead to the apoptosis of drug-resistant gastric cancer cells and the block of cell cycle at G1 phase. 5-Fu could significantly inhibit the proliferation of tumor cells after ABCC4 were silenced, at the same time, it could also suppress the growth of tumor in nude mice. Conclusion ABCC4 was overexpressed in drug-resistant gastric cancer cells. Down-regulating ABCC4 expression by RNA interference could inhibit the proliferation of multi-drug resistant gastric cancer cells, and strengthen their sensitivity to chemotherapy.