Transcription and replication of the influenza A virus RNA genome are mediated by the viral RNA polymerase from a promoter consisting of the partially base-paired 3´ and 5´ termini of viral genome segments. Here we show that transcription and replication can be uncoupled by mutation of an unpaired adenosine in the 5´-strand of the promoter. This residue is important for transcription but not replication by being essential for the cap-binding activity of the RNA polymerase.