RNA干扰（RNA interference，缩写为RNAi）是指一种分子生物学上由双链RNA诱发的基因沉默现象，其机制是通过阻碍特定基因的转译或转录来抑制基因表达。当细胞中导入与内源性mRNA编码区同源的双链RNA时，该mRNA发生降解而导致基因表达沉默。与其它基因沉默现象不同的是，在植物和线虫中，RNAi具有传递性，可在细胞之间传播，此现象被称作系统性RNA干扰（systemic RNAi）。在秀丽隐杆线虫上实验时还可使子一代产生基因突变，甚至于可用喂食细菌给线虫的方式让线虫得以产生RNA干扰现象。RNAi现象在生物中普遍存在。2006年，安德鲁·法厄（Andrew Z. Fire）与克雷格·梅洛（Craig C. Mello）由于在秀丽隐杆线虫的RNAi机制研究中的贡献而共同获得诺贝尔生理及医学奖。

RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression, typically by causing the destruction of specific mRNA molecules. Historically, it was known by other names, including co-suppression, post-transcriptional gene silencing (PTGS), and quelling. Only after these apparently unrelated processes were fully understood did it become clear that they all described the RNAi phenomenon. Andrew Fire and Craig C. Mello shared the 2006 Nobel Prize in Physiology or Medicine for their work on RNA interference in the nematode worm Caenorhabditis elegans, which they published in 1998. Since the discovery of RNAi and its regulatory potentials, it has become evident that RNAi has immense potential in suppression of desired gene. RNAi is now known as precise, efficient, stable and better than antisense technology for gene suppression.