Abstract: Abstract Aim To discuss the expression of COX-2 in the antral mucosa of pations before and after eradication of Hp infection. And the relation of this expression with chronic infectionMethod Tissues were obtained from chronic gastritis patients with Hp infection and subsequent eradication were studied. Three biopsies of antral mucosa were evaluated before and after Hp eradication. Immumohistochemical staining for COX一2 was expressed as a percentage of the total number of cells and correlated with the degree of chronic inflammation． Result C0X -2 expression could be detected before and after eradication of Hp．The expression of COX-2 was significantly higher in Hp infected mucosa compared with that Hp has been successfully eradicated(P<0．005)．The positive immunostaining of COX-2 correlated closely with the chronic inflammation score(r=0．59，P<0．05). Conclusion The overexpression of COX-2 may be one of the crucial mechanisms of Hp induced gastritis．

Key words: gastritis, Helicobacter pylori, Cyclooxygenase-2