In recent years, bacterial small regulatory RNAs (sRNAs) have been demonstrated to be powerful modulators of gene expression. Whether it is by modulating mRNA functions or protein activities, sRNAs often employ unexpected and extremely diverse mechanisms to modify the genetic output. Although the first sRNAs were characterized as molecules blocking translation of specific target mRNAs, this review will focus on an emerging subset of sRNAs that promote the decay of their target mRNAs. While the outcome resembles the RNAi silencing described in eukaryotes, the mechanism of bacterial sRNAs differs fundamentally. These sRNAs are the subject of intensive studies, which makes them the best characterized sRNAs to date.