In this study, we aimed to analyze the expression levels of the ER, PR, HER-2, and Ki-67 in the primary lesions and brain lesions in Chinese breast cancer patients with brain metastases, the differences between the primary lesions and brain lesions, and the impact of the inconsistency on patients' prognosis, which might provide a new basis for the individualized treatment options. The gene discussed is ERBB2; the disease is breast cancer.