Abstract: 【Abstract】 Objective To investigate the expression pattern and clinical significance of bone morphogenetic protein 6 (BMP6) in breast tissues. Methods The tumor and adjacent noncancerous tissues were harvested from 36 cases of breast cancer, the expression level of BMP6 mRNA of each sample was measured by quantitative RT-PCR. Immunohistochemistry study was used to examine BMP6 protein expression in 80 cases of breast cancer, then the relationship between the expression of BMP6 and relevant clinical and pathological parameters was analyzed. Results BMP6mRNA expression in breast cancer was significantly reduced when compared with normal breast tissues (P <0.01), BMP6mRNA level in estrogen receptor-positive (ER⁺) breast cancer was distinctly higher than that in ER^- breast cancer. The expression of BMP6mRNA was correlated to tumor grade (P<0.01). The expression level of BMP6 protein in breast cancer was associated to ER and PR status, histological grade and Ki-67 status (P<0.05), but not correlated to age, tumor size, human epidermal factor receptor-2 (Her2) status and molecular subtypes of breast cancer (P>0.05). Conclusion The ectopic expression of BMP6 may play an important role in the development and progression of breast cancer.