Abstract: To investigate and discuss the relationship between the expressions of E-cadherin and S100A2 genes in gastric cancer tissues, as well as their clinical characters. Methods: Semi-quantitative RT-PCR and immunohistochemistry were performed in the tumor tissues with various grades, paracancerous, and normal gastric tissues to observe the functions of E-cadherin and S100A2 in gastric cancer tissues. Sixty-four cases of tumor tissues with various grades were collected from July 2006 to December 2006 in the Liaoning Province Tumor Hospital, and 15 gastric para-neoplastic and normal gastric tissues were collected as controls. Statistical methods were used to analyze the relationship between the clinical characters of E-cadherin and S100A2 and their roles in tumor progression. Results: The length of the amplified products of E-cadherin and S100A2 was 487 bp and 362 bp, respectively. The positive expression of E-cadherin and S100A2 genes in normal gastric tissues was both 100%, whereas the expression was lower in gastric cancer tissues. Moreover, same results were obtained in the positive expression of E-cadherin and S100A2 proteins. The expression of E-cadherin and S100A2 had high consistency in gastric cancer tissues. The positive expression of E-cadherin and S100A2 proteins was statistically significant in clinical characters, such as gross type, differentiation, invasion depth, and lymph node metastasis. Conclusion: E-cadherin and S100A2 are tumor-inhibiting factors, and their expression in gastric cancer tissues decreased. The expression was negatively correlated with to tumor differentiation grade, lymph node metastasis, and invasion grade.