Abstract: Objective 　To investigate the felationship of methylation of human runt-related transcription factor 3 ( Runx3) gene on metastasis and oncogenesis of gastric arcinoma. Methods 　Using RT-PCR technique, specimens from 80 gastric cancer patients ( tumor tissues, adjacent tissues) were detected for their expression of the Runx3 gene. Meanwhile, Methylation-specific PCR was used to detect methylation of Runx3 promoter region. Results 　The expression of Runx3 gene mRNA detected in gast ric carcinoma (0. 5971 ±0. 1013) was lower than that in adjacent tissues samples (0. 8297 ±0. 2912) ( t = 6. 7480, P < 0. 05) . No methylation of Runx3 promoter was found in adjacent tissues samples. But it was found in 43 cases in 80 gastric carcinoma specimens. The rate of methylation of Runx3 promoter in gast ric carcinoma was higher than that in adjacent tissues ( P < 0. 05) . The Runx3 mRNA were down-regulated in lymphnode metastasis or poorly differentiated groups, but the Runx3 promoter methylation were detected in those groups markedly. A significant difference was noted between two groups ( P < 0. 05) . Conclusion Hypermethylation was one of reasons which induced Runx3 gene inactivation in human gastric carcinoma. Methylation of Runx3 promoter maybe correlated to on cogenesis, metastasis of gastric carcinoma.