Objective To evaluate the expression of stromal CD10 and Ezrin in ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) of breast cancer and examine their role in tumor progression. Methods Immunohistochemistry was used to detect the expression of stromal CD10 and Ezrin in 60 cases of DCIS and 60 cases of IDC. Results In IDC the expression of stromal CD10 was negative in 25 cases, weak in 18 cases, strong in 17 cases, whereas in DCIS the corresponding parts were 36 cases, 18 cases, 6 cases respectively. It was preferentially expressed in IDC compared to DCIS (Z=-2.465, P<0.05). In DCIS Ezrin localized at apical was seen in 15 cases (30.6%), at membrane in 13 cases (26.5%) and in cytoplasm in 21 cases (42.9%), whereas in IDC the corresponding parts were 5 (10. 2% ) , 6 (12. 2% ), 38 (77.6% ) respectively. The localization was significantly different between this two groups (x2=12. 477, P<0. 01). The expression of CD10 and switch of Ezrin localization were positively correlated with disease free survival (P<0. 05). There was no correlation between stromal CD10 and tumor grade, tumor size, ER and PR status, and lymph node metastases in IDC. And so did Ezrin. Conclusion The increase in the expression of stromal CD10 and the switch of Ezrin localization might participate in the process of invasion of ductal carcinoma. Key words: Breast carcinoma; Ezrin; Invasion