AbstractGenomic imprinting is an epigenetic phenomenon that results in differential expression of both alleles, depending on their parent of origin. We have recently identified many imprinted small non-coding RNA genes belonging to the C/D RNA and microRNA gene families, both of which are usually known to play key roles in post-transcriptional metabolism of specific genes (e.g. C/D RNAs guide ribose methylation of target RNAs while microRNAs elicit either translational repression or RNA interference). Although the functional and evolutionary significance of this association between C/D RNA genes, microRNA genes and genomic imprinting is still highly elusive, these observations provide a framework for further analysis of the potential role of small non-coding RNAs in epigenetic control.