1. Evidence gathered in recent years has revealed microRNAs (miRNAs) fine-tune gene expression and play an important role in various cellular processes, including cell growth, differentiation, proliferation and apoptosis. 2. The present review summarizes current knowledge of miRNA pathways in the pathogenesis of cancer, cardiac diseases, neurodegenerative diseases, diabetes, autoimmune/inflammatory diseases and infection. 3. There is considerable potential to target miRNAs as a novel approach in the treatment of human diseases. Currently, miRNA-based therapies are being examined in both animal models and human clinical trials.