PURPOSE: The significance of abnormal E-cadherin/ catenin complex expression and the correlation of each of its components in cancer remain unclear. This study aimed to characterize the clinical significance of the abnormal membrane expression of the E-cadherin/ catenin complex and the localization patterns of the beta- catenin and p120CTN in early gastric cancer. MATERIALS AND METHODS: Immunohistochemical staining for E-cadherin, alpha-, beta- and gamma-catenin and p120CTN were performed on 47 early gastric cancer specimens. The patterns of membrange expression of the E-cadherin/catenin complex, and the localization patterns of the beta-catenin and p120CTN, were semi quantitatively graded as loss, reduced, preserved or negative and positive. RESULTS: An abnormal immunoreactivity of at least one of E-cadherin/catenin complex proteins was noted in 46 (97.8%) of the 47 early gastric cancer cases. There were no significant correlations of the membrane E-cadherin/catenin expression with, either, sex, age, location, size, macroscopic type, depth of invasion or lymphovascular invasion. Abnormal expressions of membrane E-cadherin, beta-catenin and gamma-catenin were more frequent in the diffuse-type than in the intestinal type. No linear correlation was shown for the beta-catenin between the membrane and cytoplasmic expressions. Nuclear staining of the beta-catenin was observed in 5 (10.6%) cases, but nuclear staining of the p120CTN, a promotor of Kaiso transcriptional factor, was not seen. CONCLUSION: These results suggest that alterations of the E-cadherin/catenin complex may be involved in the early stages of gastric cancer. Although beta-catenin functions as a transcriptional factor, the inactivation of membrane E-cadherin does not appear to result in significant increases in the level of cytoplasmic beta-catenin. Kaiso transcriptional factor may not be involved in the early carcinogenesis of gastric cancer.