More and more miRNAs have been shown to regulate gene expression in the heart and dysregulation of their expression has been linked to cardiovascular diseases including the miR-199a/214 cluster. However, the signature of circulating miR-214 expression and its possible roles during the development of heart failure has been less well studied. In this study, we elucidated the biological and clinical significance of miR-214 dysregulation in heart failure. Firstly, circulating miR-214 was measured by quantitative PCR, and we found that miR-214 was upregulated in the serum of chronic heart failure patients, as well as in hypertrophic and failing hearts of humans and mice. Adeno-associated virus serotype 9 (AAV9)-mediated miR-214 silencing attenuates isoproterenol (ISO) infusion-induced cardiac dysfunction and impairment of cardiac angiogenesis in mice. Mechanistically, miR-214 overexpression reduces angiogenesis of HUVECs by targeting XBP1, an important transcription factor of unfolded protein response, and XBP1 silencing decreases HUVECs proliferation and angiogenesis similar to miR-214 overexpression. Furthermore, ectopic expression of XBP1 enhances endothelial cells proliferation and tube formation, and reverses anti-angiogenic effect of miR-214 over expression. All these findings suggest that miR-214 is an important regulator of angiogenesis in heart in vitro and in vivo, likely via regulating the expression of XBP1, and demonstrate that miR-214 plays an essential role in the control/inhibition of cardiac angiogenesis. J. Cell. Physiol. 230: 1964-1973, 2015. (c) 2015 The Authors. Journal of Cellular Physiology published by Wiley Periodicals, Inc.