Abstract: Eukaryotic gene expression is a complex, multistep process that needs to be executed with high fidelity and two general methods help achieve the overall accuracy of this process. Maximizing accuracy in each step in gene expression increases the fraction of correct mRNAs made. Fidelity is further improved by mRNA surveillance mechanisms that degrade incorrect or aberrant mRNAs that are made when a step is not perfectly executed. Here, we review how cytoplasmic mRNA surveillance mechanisms selectively recognize and degrade a surprisingly wide variety of aberrant mRNAs that are exported from the nucleus into the cytoplasm.