Abstract: Objective To investigate the effects of the histone deacetylation inhibitor,trichostatin A (TSA) on the expression of RASSF1A gene in human gastric cancer cell line. Methods Gastric cancer SGC-7901 cells were treated with different concentration of TSA.The apoptosis of the cells were detected by flow cytometry.RT-PCR and Western blot were applied to detect the RASSF1A mRNA and protein expression levels,respectively. Results Flow cytometry analysis showed that the apoptosis rate in SGC-7901 cells went up significantly depended on thedoseand time（P<0.05）.The mRNA and protein expression of RASSF1A gene was not detected in gastric cancer SGC-7901 cells before treatment.After treated with TSA at different concentrations and time,mRNA and protein expression of RASSF1A gene increased in a dose- and time-dependent manner (P<0.05). Conclusion It is possible that TSA induced the apoptosis of gastric cancer SGC-7901 cells by eliminating the aberrant histone acetylation status of RASSF1A gene.