Interleukin-26 (IL-26) belongs to the IL-10 cytokine family, is produced by activated T cells, and targets epithelial target cells for signal transduction. Here, we describe the IL-26 effects on the infection of culture cells with recombinant vesicular stomatitis virus (VSV), human cytomegalovirus (HCMV), and herpes simplex virus type 1 (HSV-1) expressing green fluorescent protein. After pre-incubation with recombinant IL-26 and at low multiplicity of infection, VSV showed strongly enhanced infection and replication rates as measured for infectivity, for transcript levels, and for protein expression. Control proteins did not affect VSV infection. The IL-26 effect was independent of the IL-26 receptor and neutralized by anti-IL-26 serum. Pre-incubation of VSV was much more efficient than pre-incubation of the target cells to enhance virus infection. IL-26 increased virus adsorption to target cells as shown by quantitative reverse-transcription PCR. In contrast, the infection of IL-26-treated human fibroblasts with HCMV was inhibited and the infection by HSV-1 was not altered by IL-26. Thus, IL-26 differentially modulates the infection by different enveloped viruses.