MicroRNA (miRNA)-dependent localization of targeted mRNAs to mammalian P-bodies was investigated. Argonaute proteins, key components of the RNA interference (RNAi) effector complex RISC, were found to localize to mammalian P-bodies. Reporter mRNAs targeted for translational repression by miRNAs were concentrated in P-bodies in a miRNA-dependent manner, suggesting that RISC delivers mRNAs to P-bodies, either as a cause or consequence of inhibiting protein synthesis. RNAi is a post-transcriptional gene silencing mechanism that uses small interfering RNAs (siRNAs) to cleave complementary mRNAs. miRNAs, like siRNAs, can silence gene expression but do so by repressing protein synthesis rather than cleaving mRNAs. Both miRNAs and siRNAs enter RISC, bind to Argonaute proteins, and identify their silencing targets. However, miRNAs typically pair imperfectly with their targets and do not direct cleavage. The mechanism by which miRNAs repress translation of their target mRNAs is not fully understood. However, the localization of Argonaute proteins to P-bodies suggests that miRNA-mediated repression of protein synthesis may result in the targeting of miRNA-mRNA complexes to P-bodies. Reporter mRNAs targeted for translational repression by miRNAs were found to accumulate in P-bodies, indicating that miRNA binding to Ago2 is required for its accumulation within P-bodies. The results indicate a connection between miRNA function and mammalian P-bodies. Argonaute proteins interact with P-body components such as Dcp1a and Dcp2, and these interactions are resistant to RNaseA treatment, suggesting that they occur both within and outside of P-bodies. The findings support the hypothesis that mRNAs undergoing miRNA-mediated translation repression accumulate within P-bodies in conjunction with an Argonaute-miRNA complex. This process may involve the sequestration of translationally repressed mRNAs to P-bodies, which could enhance their degradation. The study also provides insights into the functional connection between miRNA-mediated regulation and P-bodies, suggesting that miRNAs may repress translation by affecting aspects of translation or by promoting the sequestration of mRNAs to P-bodies.MicroRNA (miRNA)-dependent localization of targeted mRNAs to mammalian P-bodies was investigated. Argonaute proteins, key components of the RNA interference (RNAi) effector complex RISC, were found to localize to mammalian P-bodies. Reporter mRNAs targeted for translational repression by miRNAs were concentrated in P-bodies in a miRNA-dependent manner, suggesting that RISC delivers mRNAs to P-bodies, either as a cause or consequence of inhibiting protein synthesis. RNAi is a post-transcriptional gene silencing mechanism that uses small interfering RNAs (siRNAs) to cleave complementary mRNAs. miRNAs, like siRNAs, can silence gene expression but do so by repressing protein synthesis rather than cleaving mRNAs. Both miRNAs and siRNAs enter RISC, bind to Argonaute proteins, and identify their silencing targets. However, miRNAs typically pair imperfectly with their targets and do not direct cleavage. The mechanism by which miRNAs repress translation of their target mRNAs is not fully understood. However, the localization of Argonaute proteins to P-bodies suggests that miRNA-mediated repression of protein synthesis may result in the targeting of miRNA-mRNA complexes to P-bodies. Reporter mRNAs targeted for translational repression by miRNAs were found to accumulate in P-bodies, indicating that miRNA binding to Ago2 is required for its accumulation within P-bodies. The results indicate a connection between miRNA function and mammalian P-bodies. Argonaute proteins interact with P-body components such as Dcp1a and Dcp2, and these interactions are resistant to RNaseA treatment, suggesting that they occur both within and outside of P-bodies. The findings support the hypothesis that mRNAs undergoing miRNA-mediated translation repression accumulate within P-bodies in conjunction with an Argonaute-miRNA complex. This process may involve the sequestration of translationally repressed mRNAs to P-bodies, which could enhance their degradation. The study also provides insights into the functional connection between miRNA-mediated regulation and P-bodies, suggesting that miRNAs may repress translation by affecting aspects of translation or by promoting the sequestration of mRNAs to P-bodies.