Cancer stem cells (CSCs), or cancer cells with stem cell properties, represent a small fraction of tumor bulk and are thought to be responsible for tumor formation and metastasis. However, the mechanisms of how CSCs are generated and regulated at the molecular level are poorly understood. Recent progress has highlighted the significance of microRNAs (miRNAs) in cancer progression and CSC function. The function and dysfunction of miRNAs in the development of cancer and CSCs have become a burgeoning area of intense research. A new finding has elucidated a mechanism of antagonistic miRNA crosstalk whereby one miRNA can inhibit another miRNA in regulating CSCs. Herein we make this short review to summarize the current understanding of the regulatory mechanisms of miRNAs in cancer and CSCs and discuss the implications of targeting CSCs for cancer therapeutics. J. Cell. Biochem. 115: 605–610, 2014. © 2013 Wiley Periodicals, Inc.