MicroRNAs (miRNAs) are a class of non-protein coding genes with a growing importance in regulatory mechanisms of gene expression related to brain function and plasticity. Considering the relative lack of success of the analysis of variations in candidate protein coding genes and of genome-wide association studies to identify strong risk factors for common psychiatric disorders (PDs), miRNA genes are of particular interest for the field of psychiatric genetics as deregulation of the rate of transcription or translation of a normal gene may be phenotypically similar to disruption of the gene itself. In this paper, we review the current knowledge on the contribution of miRNAs in basic mechanisms of brain development and plasticity and their possible involvement in the pathogenesis of several PDs. Since future functional and genomic explorations of brain expressed miRNAs, and other types of non-coding RNAs, may identify additional candidate genes and pathways for common PDs, we believe that implementing additional strategies to further elucidate the role of miRNAs in the etiology of common PDs is of great importance. (c) 2010 Wiley-Liss, Inc.