Current knowledge on neurobiology and genetics of psychiatric disorders are limited. MicroRNA are approximately 22 nucleotides long. Their biogenesis starts in the nucleus and maturation continues in the cytoplasm of cells. MicroRNA influence the genes in posttranscriptional level that commonly appear as inhibition. MicroRNAs are crucial for neurogenesis, synaptic plasticity and several neurobiological processes. For psychiatric disorders they are found to be dysregulated in both central nervous system and peripheral tissues. Knowledge and research on microRNAs keep evolving day by day. Although they have been investigated widely, we still need extensive research on this field.