Cancer stem cells are a kind of cancer cell group with the ability of self-renewal and various diferentiation potentials.Recent studies have implicated that they play a significant role in tumor formation,metastasis,resistance to anticancer therapies and cancer recurrenee.Many studies show that microRNAs are involved in the maintenance,growth and behavior of breast cancer stem cells (BCSCs),paving a new way for diagnosis,prognosis and therapy of breast cancer.