Gene expression programs undergo constant regulation to quickly adjust to environmental stimuli that alter the physiological status of the cell, like cellular stress or infection. Gene expression is tightly regulated by multilayered regulatory elements acting in both cis and trans. Posttranscriptional regulation of the 3' untranslated region (UTR) is a powerful regulatory process that determines the rate of protein translation from mRNA. Regulatory elements targeting the 3' UTR include microRNAs, RNA-binding proteins, and long noncoding RNAs, which dramatically alter the immune response. We provide an overview of our current understanding of posttranscriptional regulation of immune gene expression. The focus of this review is on regulatory elements that target the 3' UTR. We delineate how the synergistic or antagonistic interactions of posttranscriptional regulators determine gene expression levels and how dysregulation of 3' UTR-mediated posttranscriptional control associates with human diseases.