miR-27 is a family of microRNA precursors found in animals, including humans. MicroRNAs are typically transcribed as ~70 nucleotide precursors and subsequently processed by the Dicer enzyme to give a ~22 nucleotide product. The excised region or, mature product, of the miR-27 precursor is the microRNA mir-27. Herpesvirus saimiri expresses several non-coding RNAs (HSURs) which have been found to significantly reduce the level of mir-27 in a host cell. It has been proposed that miR-27 operates together with miR-23 and mir-24 in a co-operative cluster.