Objective To investigate the correlation and significance of cyclooxygenase-2 (COX-2) an d gastric cancer-associated antigen MG7(MG7-Ag) in gastric carcinoma and non- cancerous tissues. Methods Avidin-biotin peroxidase complex immunohistochemical method was adopted to exam ine the expression of COX-2 and MG7-Ag in the gastric mucosa of 100 patients w ith gastric carcinoma. The Helicobacter pylori(H. pylori) infection in gastr ic carcinoma was determined by blue amino toluene stain and modified Giemsa stai n. Results The positive rates of COX-2 and MG7-Ag in gastric carcinoma were 88.0% and 92. 0% respectively. From chronic superficial gastritis, chronic atrophic gastritis, intestinal metaplasia to dysplasia, the expression of COX-2 and MG7-Ag showed a n ascending tendency. Both COX-2 and MG7-Ag were expressed at higher level in cases with lymph nodes or distal organs metastasis than those without (P