Abstract: Objective: To investigate the correlation between the expression of the BI-1 gene and the receptors for estrogen and progestogen in breast cancer and its significance. Methods: Immunohis-tochemical methods were used to detect the expression of the BI-1 gene and the receptors for estrogen and progestogen in breast cancer. Results: The positive rates of expression of the BI-1 gene in breast cancer and matched normal tissues were 77.08% and 18.75%, respectively. The difference was statisti-cally significant (P<0.05). The positive rate of expression of the BI- 1 gene was higher in the group with no expression of estrogen receptor(94.74%) than that in the group with detectable expression of estrogen receptor (65.52%). There was no statistically significant difference in BI-1 expression between the pro-gestogen receptor (PR)-positive and PR- negative groups(P>0.05). The positive rate of expression of the BI-1 gene was also higher in the group with lymph node metastasis than in the group without lymphnode metastasis. The differences were statistically significant (P<0.05). Conclusion: Detecting expres-sion of the BI-1 gene in combination with estrogen receptor is an important indicator for prognosis of breast cancer.