The recent discovery of microRNAs (miRNAs) has caused the traditional central dogma of molecular biology to be rewritten. miRNAs are small, noncoding pieces of ribonucleic acid that exert control over gene expression at the posttranscriptional level. They appear to play important roles in the normal development and functioning of the nervous system and in disease states. To understand future diagnostic and therapeutic advances arising from the study of miRNAs, it is crucial that neurosurgeons understand what miRNAs are, how they function, and the role they play in diseases of the nervous system. This article serves as a basic introduction to miRNAs and their ever-expanding role in the neurological sciences.