Abstract: Objective To investigate the promoter methylation and expression of RASSF1A gene in gastric cardiac adenocarcinoma(GCA). Methods We used MSP approach,RT-PCR and immunohistochemistry method respectively to examine the methylation status of the 5' CpG island of RASSF1A gene and its expression at mRNA and protein levels in tumors and corresponding normal tissues. Results RASSF1A promoter was methylated in 54/92 (58.7%) tumor specimens, which was significantly higher than that in corresponding normal tissues（P<0.001）. Methylation frequencies of stage Ⅲ and Ⅳ tumor tissues were significantly higher than those in stageⅠandⅡtumor tissues（P<0.05）. By immunostaining,43/92(46.7%) tumor tissues demonstrated heterogeneous, positive immunostaining of tumor tissues. The expression of RASSF1A at mRNA levels were significantly reduced compared to matched normal tissues（P<0.001,respectively）. Protein expressions of RASSF1A in stage Ⅲ and Ⅳ tumor tissues were significantly lower than those in stageⅠandⅡtumor tissues（P<0.05）.RASSF1A mRNA expressions in methylation group of GCA were significantly different from those in unmethylation group（P<0.001）. Conclusion Epigenetic silencing of RASSF1A gene expression by promoter hypermethylation may play an important role in gastric cardiac adenocarcinoma.