Objective: The aim of our study was to observe the expressions and clinical Significance of E-cadherin, β-catenin and E-cadherin-catenins complex in breast cancer and precancerous lesions, and analyze the relationship between the ex-pressions and clinicopathological features in breast cancer. Methods: Immunhistochemical UltraSensitiveTM S-P method was employed to detect the expression of E-cadherin, β-catenin and E-cadherin-catenins complex in 128 cases of invasive ductal carcinomas, 89 cases of ductal carcinoma in situ and 57 cases of atypical ductal hyperplasia, 53 cases of usual ductal hyper-plasia breast tissues were selected as a control group. The express of E-cadherin, β-catenin and their relationship with mult biological parameters including histological grade, region lymph node metastasis, distant metastasis and recurrence on files were also assessed. Results: (1) The staining patterns character of E-cadherin, β-catenin and E-cadherin-catenins complex:In UDH breast tissues, E-cadherin and a-catenin were expressed on cellmembrane of ductal and acinic cells, showing cellular contour and border among cells. The abnormal expression of the three proteins occurred in breast invasive ductal carcinomas, ductal carcinoma in situ and atypical ductal hyperplasia tissues, showing cytoplasmic or nuclear staining, decrease and loss of cytomembrane staining. (2) The abnormal expression rates of E-cadherin, β-catenin and E-cadherin-catenins complex in invasive ductal carcinomas were 53.91%, 65.63% and 81.25%, which were significantly higher than that in ductal carcinoma in situ, atypical ductal hyperplasia, usual ductal hyperplasia tissues (P 0.05). (3) There was a significantly dif erence in the mean E-cadherin, β-catenin and E-cadherin-catenins complex frequency between estrogen receptor & progesterone receptor positive IDC group and negative group, epidermal growth factor receptor type 2 (HER2/neu) positive and negative groups, Ki-67 proliferation index ≤ 14% and> 14% groups, histological grade (I + II) and grade III invasive ductal carcinomas groups, with lymph node metastasis, distant metastasis and recurrence groups (P 50 years), tumor diameter (≤2 cm vs > 2 cm) (P > 0. 05). Conclusion: In breast cancer, the expressions of E-cadherin, β-catenin and E-cadherin-catenins complex are abnormal y decreased and are correlated with pathology grade, dif erentiation disturbance and metastasis. E-cadherin and β-catenin may be as the predictors for prognosis. Combined detection may improve accuracy and sensitivity of predicting metastasis and prognosis of breast Cancer.