Because of increased insensitivity or resistance to chemical treatment in tumor patients, specific apoptotic gene silence may provide a rational approach for the development of novel therapeutic strategies. This study was to investigate whether downregulation of Bcl-2 expression by small interfering RNA (siRNA) against the Bcl-2 gene would enhance the apoptosis and sensitivity of gastric adenocarcinoma SGC-7901 cell to 5-Fluorouracil. Transfections of SGC-7901 cells with siRNA were performed using cationic liposomes. Sequence-specific downregulation of Bcl-2 expression was measured by RT-PCR and Western blot analysis. Cell proliferation assay was determined by MTT assay and apoptotic cell rates were determined by flow cytometry assay. Results showed that the siRNA could downregulate Bcl-2 expression, which increased apoptosis and sensitivity of SGC-7901 cell to 5-Fluorouracil (P<0.05). This study indicated that inhibition of Bcl-2 expression by siRNA would be useful a new useful protocol to increase the effect of 5-Fluorouracil on treatment of gastric adenocarcinoma, which may play an important role in developing novel therapeutic strategies in the future.