Objective: To observe the influence of interference of Yes-associated protein (YAP) gene expression on proliferation and apoptosis in breast cancer cells. Methods: Using a retrovirus-mediated method, breast cancer MCF-7 cells were transfected with YAP shRNA (experimental group) or negative control shRNA (control group), respectively. After that, the interference efficacy was evaluated via qRT-PCR and Western blot analysis, cell proliferative ability was determined by bromodeoxyuridine (BrdU) incorporation assay and MTT assay, and cell apoptosis was detected with flow cytometry and DAPI staining, respectively. Results: Interference efficacy determination showed that YAP mRNA expression level was significantly decreased (P<0.05), and YAP protein expression was also remarkably down-regulated in MCF-7 cells in experimental group compared with control group at 72 h after transfection. Cell proliferation assay showed that BrdU incorporation level and OD value in experimental group were significantly reduced compared with control group (both P<0.05), and the ratio of proliferation inhibition in experimental group at 24, 48, 72 h after transfection was 19.1%, 38.5% and 53.5%, respectively. Cell apoptosis analysis showed that the apoptosis rate and number of apoptotic cells in experimental group were significantly increased compared with control group (both P<0.05).Conclusion: Interference of YAP gene expression can effectively inhibit the proliferation and accelerate apoptosis in breast cancer cells, and YAP may probably a potential therapeutic target for breast cancer.