Gene silencing is the regulation of gene expression in a cell to reduce or eliminate the production of a protein from its corresponding gene. It is considered a gene knockdown mechanism, since the expression of a gene is reduced by at least 70% but is not completely eliminated.

Gene silencing can occur during either transcription or translation. Common transcriptional methods include genomic imprinting, paramutation, transposon silencing, transgene silencing, as well as RNA-directed DNA methylation, while examples of post-transcriptional methods are RNA interference, RNA silencing and nonsense mediated decay.