RNA激活（RNA activation, RNAa) 是一种由小分子RNA介导的基因表达上调机制。RNAa是由Li等于2006年首先在人细胞中发现并命名的。随后，其他研究小组也报道了相似的结果,证明了RNAa存在于包括人在内的灵长类、大鼠及小鼠等哺乳类细胞。RNAa是由靶向特定的基因启动子区域的双链小RNA（dsRNA）分子介导。这类针对基因非编码区的dsRNA被称为agRNA（antigene RNA）, 其中能诱导RNAa现象（激活基因表达）的agRNA被称为small activating RNA （saRNA）。

RNA activation (RNAa) is a small RNA-guided and Argonaute-dependent gene regulation phenomenon in which promoter-targeted short double-stranded RNAs (dsRNAs) induce target gene expression at the transcriptional/epigenetic level. RNAa was first reported in a 2006 PNAS paper by Li et al. who also coined the term "RNAa" as a contrast to RNA interference (RNAi) to describe such gene activation phenomenon. Soon after, several groups made similar observation in different mammalian species including human, non-human primates, rat and mice, suggesting that RNAa is a general gene regulation mechanism conserved at least in mammals. In these studies, upregulation of gene expression is achieved by targeting selected promoter regions using either synthetic 21-nucleotide dsRNAs or vector expressed small hairpin RNAs (shRNAs). Such promoter targeted dsRNAs have been termed antigene RNA (agRNAs) or small activating RNA (saRNA).