Innate immunity is considered to provide the initial defense against infections by viruses,bacteria,fungi,and protozoa.Detection of the signature molecules of invading pathogens by front-line defense cells via various germline-encoded pattern recognition receptors(PRRs) is needed to activate intracellular signaling cascades that lead to transcriptional expression of inflammatory mediators to coordinate the elimination of pathogens and infected cells.To maintain a fine balance between protective immunity and inflammatory pathology upon infection,the innate signaling pathways in the host need to be tightly regulated.MicroRNAs(miRNAs),a new class of small non-coding RNAs,have been recently shown to be potent modulators that function at post-transcriptional levels.Accumulating evidence demonstrates that the involvement of microorganismencoded and host miRNAs might play instructive roles in the immune response upon infection.Here,we discuss the current knowledge of miRNAs in the regulation of immune response against infections. Innate immunity is considered to provide the initial defense against infections by viruses, bacteria, fungi, and protozoa. Detection of the signature molecules of invading pathogens by front-line defense cells via various germline-encoded pattern recognition receptors (PRRs) is needed to activate intracellular signaling cascades that lead to transcriptional expression of inflammatory mediators to coordinate the elimination of pathogens and infected cells. To maintain a fine balance between protective immunity and inflammatory pathology upon infection, the innate signaling pathways in the host need to be tightly regulated. MicroRNAs ( miRNAs), a new class of small non-coding RNAs, have been recently shown to be potent modulators that function at post-transcriptional levels. Accumulating evidence demonstrates that the involvement of microorganismencoded and host miRNAs might play instructive roles in the immune response upon infection .Here, we discuss the current knowledge of miRNAs in the regulation of immune response against infections.