Background:Gastric cancer is one of the malignant tumors with highest morbidity and mortality,and the early change of molecular marker in gastric mucosal lesion is the hot spot of gastric cancer study. Aims:To investigate the expressions and clinical significance of trefoil factor 2(TFF2),claudin 18(CLDN18),mucin 5AC(MUC5AC)in gastric mucosal lesions. Methods:Gastroscopy biopsies and surgery specimens from Dec. 2008 to May 2009 at Inner Mongolia People’s Hospital were collected,including 20 normal gastric mucosal tissues,20 intestinal metaplasia tissues,11 dysplasia tissues and 20 gastric cancer tissues. The protein expressions of TFF2, CLDN18, MUC5AC were determined by immunohistochemical SP method. Results:The positive expression rates of TFF2,CLDN18 and MUC5AC in normal gastric mucosal tissues were all 100% ,and were gradually decreased in the order of intestinal metaplasia,dysplasia and gastric cancer tissue,the differences were statistically significant(P < 0. 01). Conclusions:Expressions of TFF2,CLDN18 and MUC5AC protein are closely related to the degree of malignancy of gastric mucosal lesions,and can be considered as a potential biological marker for predicting the development and prognosis of gastric cancer.