Abstract: Objective To study the correlation between the expression of HDAC3 and the occurrence,development and prognosis of gastric cancer. Methods The gastric cancer tissue microarray containing 111 samples with following-up information was utilized.The expression of HDAC3 protein was detected by immunohistochemistry and the correlation between the experimental data and clinical parameters as well as prognosis of gastric cancer was analyzed by SPSS software. Results HDAC3,specifically expressed in the nucleus,was significantly higher in gastric cancer tissues than para-carcinoma tissues(P=0.001).Clinical index correlation analysis showed that HDAC3 expression was positively correlated with T staging,M staging,N staging and clinical staging of gastric cancer patients significantly(r>0.2,P<0.05).Subsequent survival analysis also confirmed that the prognosis of patients with high HDAC3 expression were significantly worse(6.3% vs. 22.0%,P=0.029),in addition,age,tumor size,histological grade,T stage,N staging and clinical staging index were also significantly negative correlated with patients' survival time(P<0.05).Then,we included these seven prognostic factors in the Cox multivariate regression analysis.The results showed that only the T staging(P=0.043) but not HDAC3 and all other indicators was independent prognostic factor(P>0.05). Conclusion We speculate that the gastric cancer cells over-expressing of HDAC3 may have stronger invasion and migration ability,and could be easily transferred to the surrounding and distant tissues and organs,thus reducing the patient's lifetime.It is also possible that HDAC3 might be not in the leading role in this cancer promoting process which may be regulated by other gene and signaling network.Next,we plan to establish HDAC3 over expression gastric cancer cell lines,giving anticancer drugs and HDAC3 inhibitor treatment,in order to further study the specific molecular signaling network of HDAC3 in gastric cancer.