It is well established that gene expression patterns are substantially altered in cardiac hypertrophy and heart failure, but the reasons for such differences are not clear. MicroRNAs (miRNAs) are short noncoding RNAs that provide a novel mechanism for gene regulation. The goal of this study was to comprehensively test for alterations in miRNA expression using human heart failure samples with an aim to build signaling pathway networks using predicted targets for the miRNAs and to identify nodal molecules that control these networks. Genome-wide profiling of miRNAs was performed using custom-designed miRNA microarray followed by validation on an independent set of samples. Eight miRNAs are significantly altered in heart failure of which we have identified two novel miRNAs that are yet to be implicated in cardiac pathophysiology. To gain an unbiased global perspective on regulation by altered miRNAs, predicted targets of eight miRNAs were analyzed using the Ingenuity Pathways Analysis network algorithm to build signaling networks and identify nodal molecules. The majority of nodal molecules identified in our analysis are targets of altered miRNAs and are known regulators of cardiovascular signaling. A heart failure gene expression data base was used to analyze changes in expression patterns for these target nodal molecules. Indeed, expression of nodal molecules was altered in heart failure and inversely correlated to miRNA changes validating our analysis. Importantly, using network analysis we have identified a limited number of key functional targets that may regulate expression of the myriad proteins in heart failure and could be potential therapeutic targets.Heart failure has been classified as an epidemic of the 21st century and is now the major cause of morbidity in the elderly in the United States. End-stage heart failure is characterized by significantly perturbed neurohormonal and mechanical (hemodynamic) stimuli to the heart. The altered pathological signaling leads to remodeling of the heart with adaptive to maladaptive hypertrophy transitioning into dilated cardiomyopathy (DCM).3 DCM is the most common and well documented outcome of various deleterious stimuli the heart perceives (1). DCM is characterized clinically by left ventricular dilatation, ventricular wall thinning, and homogeneous myocardial dysfunction leading to congestive heart failure (1). The myocytes under the continuously changing conditions of biomechanical stress during this transition undergo a remodeling process through the activation of intracellular signaling pathways and transcriptional mediators (2). The pathological end-stage DCM is a result of the concomitant cross-talk between various deleterious and compensatory signaling pathways. The balance between these two dynamic pathways ultimately determines the progression of the pathology. Despite significant advances in identification of genes and signaling pathways, the overall complexity of hypertrophic remodeling suggests the involvement of additional global regulatory mechanisms...