micro RNAs(mi RNAs) are powerful regulators of posttranscriptional gene expression and play an important role in pathophysiological processes. Circulating mi RNAs can be quantified in body liquids and are promising biomarkers in numerous diseases. In cardiovascular disease mi RNAs have been proven to be reliable diagnostic biomarkers for different disease entities. In cardiac fibrosis(CF) and heart failure(HF) dysregulated circulating mi RNAs have been identified,indicating their promising applicability as diagnostic biomarkers. Some mi RNAs were successfully tested in risk stratification of HF implementing their potential use as prognostic biomarkers. In this respect mi RNAs might soon be implemented in diagnostic clinical routine. In the young field of mi RNA based research advances have been made in identifying mi RNAs as potential targets for the treatment of experimental CF and HF. Promising study results suggest their potential future application as therapeutic agents in treatment of cardiovascular disease. This article summarizes the current state of the various aspects of mi RNA research in the field of CF and HF with reduced ejection fraction as well as preserved ejection fraction. The review provides an overview of the application of circulating mi RNAs as biomarkers in CF and HF and current approaches to therapeutically utilize mi RNAs in this field of cardiovascular disease. MicroRNAs (mi RNAs) are powerful regulators of posttranscriptional gene expression and play an important role in pathophysiological processes. Circulating mi RNAs can be quantified in pathophysiological processes. Diagnostic biomarkers for different disease entities. In cardiac fibrosis (CF) and heart failure (HF) dysregulated circulating mi RNAs have been identified, indicating their promising applicability as diagnostic biomarkers. Some mi RNAs were successfully tested in risk stratification of HF apply their potential use In the respect miRNAs might soon be implemented in diagnostic clinical routine. In the young field of mi RNA based research advances have been made in identifying miRNAs as potential targets for the treatment of experimental CF and HF. Promising study results suggest their potential future application as therapeutic agents in treatmen t of cardiovascular disease. This article summarizes the current state of the various aspects of mi RNA research in the field of CF and HF with reduced ejection fraction as well as preserved ejection fraction. The review provides an overview of the application of circulating mi RNAs as biomarkers in CF and HF and current approaches to therapeutically utilize miRNAs in this field of cardiovascular disease.