microRNAs are a subclass of noncoding RNAs which have been demonstrated to play pivotal roles in multiple cellular mechanisms. microRNAs are small RNA molecules of 22-24 nt in length capable of modulating protein translation and/or RNA stability by base-priming with complementary sequences of the mRNAs, normally at the 3'untranslated region. To date, over 2,000 microRNAs have been already identified in humans, and orthologous microRNAs have been also identified in distinct animals and plants ranging a wide vast of species. High-throughput analyses by microarrays have become a gold standard to analyze the changes on microRNA expression in normal and pathological cellular or tissue conditions. In this chapter, we provide insights into the usage of this uprising technology in the context of cardiac development and disease.