Abstract MicroRNAs (miRNAs) are a large family of short, single-stranded, highly conserved noncoding RNAs involved in gene regulation that can regulate gene expression through sequence-specific base pairing with target messenger RNAs (mRNAs). miRNAs have been implicated in the development of a wide variety of cancers as well as heart disease and other diseases. This review describes the role of miRNAs in human disease, methodology for evaluating miRNA gene expression, and the potential role of miRNAs as therapeutic agents and targets for the treatment of disease.