OBJECTIVE: To explore the expressions of FHIT, BCRP, and Bcl-2 proteins in breast invasive ductal carcinoma (IDC) and the relationships with clinical pathological factors. STUDY DESIGN: The expressions of FHIT, BCRP, and Bcl-2 proteins in 84 cases of surgically resected primary breast IDC tissues and another 36 cases of normal breast tissues collected about 3 cm away from the neoplastic foci and pathologically confirmed as normal were detected with the immunohistochemical streptavidin-peroxidase method to analyze the relationships between the 3 proteins and the pathological characteristics of breast IDC. RESULTS: The positive expression rates of FHIT, BCRP, and Bcl-2 were 42.86%, 72.62%, and 61.90%, respectively, in the breast IDC group and 72.22%, 36.11%, and 38.89%, respectively, in the normal control group, between which the differences were statistically significant (p < 0.05). In the breast IDC group the expressions of the 3 proteins were correlated with lymphatic metastasis and recurrence but were not significantly correlated with the expression of estrogen receptor, progesterone receptor, or proto-oncogene human epidermal growth factor receptor 2. The expression of FHIT was negatively correlated with the expression of Bcl-2 (r=-0.322, -0.389), but BCRP and Bcl-2 expressions were positively correlated (r=0.276). CONCLUSION: Abnormal expressions of FHIT, BCRP, and Bcl-2 proteins may play important roles in the onset and progression of breast IDC. © Science Printers and Publishers, Inc.