Abstract: Human breast carcinomas are very heterogeneous, with approximately 18histological types and at least 5 molecular subtypes. Breast cancer stem cells (CSCs) termed for a small population of cancer cells have self-renewal ca-pacities and the ability to recapitulate all cell types within an individual tumor. They have been demonstrated to have tu-mor-initiating properties in breast cancer. CD44+/CD24-/low is the biological marker for breast CSCs. About 30% of breast cancer patients have CD44+/CD24-/low phenotype. Histopathology is related to CD 44+/CD24-/low, in which invasive ductal carcinoma is the highest ( 78% ), medullary carcinoma (11% ) and invasive lobular carcinoma (7% ) are in the next place. CD44+/CD24-/low is related to molecular subtypes in which basal-like type is the most common for CD 44+/CD24-/low phe-notype. Breast CSCs are usually ER (-) and PR (-), but they can divide into ER+ and PR+ progeny cells. HER 2 overexpres -sion can interact with CSCs pathway and thus contribute to breast tumorgenesis and development. However, CD 44+/ CD24-/low phenotype is related to HER 2-negative breast cancer. This article reviews the progress in the research on breast cancer stem cells and discusses its potential for better diagnosis and treatment of breast cancer.