Multiple structural changes are known to occur in a failing heart. Myocyte hypertrophy, cardiomyocyte apoptosis, interstitial fibrosis, reduced capillary density, and activation of the immune system are all involved in the pathogenesis and progression of heart failure (HF). The molecular mechanisms underlying these changes of the myocardium have been extensively studied, and many pathways involved in these processes have been uncovered. Recently, it has become evident that a novel class of small non-coding RNAs, called miRNAs, also plays a key role in these structural changes of the heart. This review summarizes the current insights on the role of miRNAs outside myocytes in the heart. Specifically, we will discuss miRNA function in fibroblasts, endothelial cells and immune cells in response to myocardial stress as occurs after myocardial infarction and in the pathogenesis of HF.