MicroRNAs (miRNAs or miRs) are short, highly conserved noncoding RNAs that regulate gene expression at the post-transcriptional level by inhibiting translation or promoting the degradation of target mRNA. Even though the field of miRNA biology is relatively young, growing lines of evidence suggest that miRNAs play a key role pathogenesis of heart failure through their ability to regulate genes that govern the process of adaptive and maladaptive cardiac remodeling. Herein, we review the biology of miRNAs in relation to their role in modulating various aspects of the cardiac remodeling process, as well as discuss the potential applications of miRNA biology to the field of heart failure.