Transposable elements (TEs) are DNA elements found in the genomes of various organisms. TEs have been highly conserved during evolution, suggesting that they confer advantageous effects to their hosts. However, due to their ability to transpose into virtually any locus, TEs have the ability to generate deleterious mutations in the host genome. In response, a variety of different mechanisms have evolved to mitigate their activities. A main defense mechanism is RNA silencing, which is a gene silencing mechanism triggered by small RNAs. In this review, we address RNA silencing mechanisms that silence retrotransposons, a subset of TEs, and discuss how germline and somatic cells are equipped with different retrotransposon silencing mechanisms.