Abstract: Objective To study the molecular forms of TFF1 in normal gastric mucosa and its expression in normal, gastric carcinoma, atypical hyperplasia, and intestinalized gastric mucosa. Methods The molecular forms of TFF1 in normal gastric mucosa was observed by western blotting. The expression of TFF1 in normal, gastric carcinoma, atypical hyperplasia, and intestinalization gastric mucosa was assayed immunohistochemically. Results TFF1 existed in normal gastric mucosa in forms of monomer, dimer and 21-kD TFF1 complex, with the last being the richest. TFF1 was expressed mainly in the epithelial cytoplasm of the mucosa in the gastric body and antrum, especially around the nucleus, and the closer to the lumen, the higher the expression. TFF1 expression in the tissues adjacent to gastric carcinoma was higher than that in normal gastric mucosa (P<0.001), and the expression in gastric adenocarcinoma was positively correlated to differentiation of adenocarcinoma. No TFF1 was expressed in poorly differentiated adenocarcinoma. The expression of TFF1 in moderate and well differentiated adenocarcinoma was a little lower than that in normal mucosa (P>0.05). The gastric mucosa with atypical hyperplasia had significantly higher TFF1 expression than normal gastric mucosa (P<0.001), and TFF1 was not detected in intestinalized gastric mucosa. There was no significant difference in TFF1 expression between gastric mucosa around the intestinalized tissues and normal gastric mucosa (P>0.05). Conclusions TFF1 plays an important part in protection and restitution of the gastric mucosa, and TFF1 may be related to suppression and differentiation of carcinoma.