Abstract: Objective To reveal whether dasatinib, an inhibitor of kinase c-Src, enhances the sensitivity of BGC-823 cells to trastuzumab． Methods The level of endogenous proteins c-Src and HER2 in gastric cancer cell lines BGC-823, SGC-7901, MGC-803, and NCI-N87 were detected by western blot． The concentration-effect curves of dasatinib and trastuzumab were determined by MTT assay． The regulatory role of dasatinib on trastuzumab to BGC-823 cells was identified by MTT, colony formation and apoptosis assays． Results Dasatinib and trastuzumab inhibited BGC-823 cells survival in a dose-dependent manner． The IC₂₅(25% inhibitory effect concentration) of dasatinib was 0．47±0．10μmol/L and IC₅₀(50% inhibitory effect concentration) of trastuzumab was 2．25±0．33μg/ml． Treatment of 0．2μmol/L dasatinib enhanced the effect of trastuzumab on BGC-823, and the IC₅₀of trastuzumab decreased from 2．30±0．22μg/ml to 0．31±0．05μg/ml． Conclusion Dasatinib enhances the effect of trastuzumab on BGC-823 cells．