The aim of the study was to investigate the effects of estrogen receptor (ER) subtypes (ERα and ERβ) on breast cancer development and progression. The expression level of ERα and ERβ in breast cancer tissues and paired normal breast tissues were detected by Western blot analysis and immunohistochemistry (IHC) staining. The features of ERα and ERβ status in cancer tissues or normal breast tissues and the correlations between clinicopathological characteristics and prognosis were analyzed. The expression levels of ERα and ERβ in breast cancer tissues are significantly lower than those in the paired normal tissues. The expression of ERβ is decreased more than that of ERα. ERα expression levels in cancer tissues are associated with tumor diameter, tumor-node-metastasis (TNM) stage, and progesterone receptor (PR) status. However, ERβ expression levels in cancer tissues are not correlated with clinicopathological factors of patients with breast cancer. In conclusion, ER subtypes might play different roles in the development of breast cancer.