Vesicular stomatitis virus (VSV) (a rhabdovirus) and its variant VSV-ΔM51 are widely used model systems to study mechanisms of virus-host interactions. Here, we investigated how the cell cycle affects replication of VSV and VSV-ΔM51. We show that G2/M cell cycle arrest strongly enhances the replication of VSV-ΔM51 (but not of wild-type VSV) and Sendai virus (a paramyxovirus) via inhibition of antiviral gene expression, likely due to mitotic inhibition of transcription, a global repression of cellular transcription during G2/M phase. Our data suggest that the G2/M phase could represent an “Achilles’ heel” of the infected cell, a phase when the cell is inadequately protected. This model could explain at least one of the reasons why many viruses have been shown to induce G2/M arrest, and it has important implications for oncolytic virotherapy, suggesting that frequent cell cycle progression in cancer cells could make them more permissive to viruses.