：Objective To study the relationship of expression ER with gastric mucosal carcinogenesis and behavior of gastric carcinoma. Methods S-P immunohistochemistry method. Results The study showed expression of ER was negative in chronic superficial gastritis and dysplasia.The positive rate of ER in gastric carcinomas was 40% . Statistically

the positive rates of ER in advanced gastric carcinomas were significantly higher than those in early gastric carcinomas（Ｐ<0.05）. The positive rates of ER in the group with lymph node metastasis were significantly higher than those in the group without lymph node metastasis (Ｐ<0.05). Conclusion ER might play important roles in the process of carcinogenesis of gastric mucosa ，and be used as useful markers for the assessment of biological behavior of gastric carcinoma .