Gene expression can be regulated at multiple levels, including transcription, RNA processing, RNA localization, translation and, finally, RNA turnover. RNA degradation may occur at points along the processing pathway or during translation as it undergoes quality control by RNA surveillance systems. Alternatively, mRNAs may be subject to regulated degradation, often mediated by cis-encoded determinants in the mRNA sequence that, through the recruitment of trans factors, determine the fate of the mRNA. The aim of the present review is to highlight mechanisms of regulated and quality-control RNA degradation in eukaryotic cells, with an emphasis on mammals.