Multiple studies have consistently established that miR (microRNA)‐210 induction is a feature of the hypoxic response in both normal and transformed cells. Here, we discuss the emerging biochemical functions of this miRNA and anticipate potential clinical applications. miR‐210 is a robust target of hypoxia‐inducible factor, and its overexpression has been detected in a variety of cardiovascular diseases and solid tumors. High levels of miR‐210 have been linked to an in vivo hypoxic signature and associated with adverse prognosis in cancer patients. A wide spectrum of miR‐210 targets have been identified, with roles in mitochondrial metabolism, angiogenesis, DNA repair, and cell survival. Such targets may broadly affect the evolution of tumors and other pathological settings, such as ischemic disorders. Harnessing the knowledge of miR‐210's actions may lead to novel diagnostic and therapeutic approaches. © 2011 IUBMB IUBMB Life, 63(2): 94–100, 2011