Abstract: Purpose: To investigate cyclooxygenase - 2(COX - 2) protein expression in gastric carcinoma and its relationship with the helicobacter pylori(Hp) infection,supply rationale for chemoprevention of gastric carcinoma. Methods: 35 biopsy specimen from gastric carcinoma,18 from gastric dysplasia and 15 from patients with chronic gastritis were examined for COX-2 protein expression by immunohistochemistry ,and Hp infection condition by urease test, respectively. Results: Positive rates of COX - 2 expression in gastric carcinoma group,gastric dysplasia group and chronic gastritis group were 85.71 ％,72.22 ％ and 6.67 ％,respectively. 35 patients in COX - 2 positive cases were Hp positive. Conclusion: COX-2 protein overexpression may contribute to an early event of gastric cancer development and Hp infection may be one of the mechanisms of COX - 2 overexpression.

Key words: cyclooxygenase - 2, Helicobacter pylori, gastric carcinoma, gastric dysplasia