Abstract . Homologous recombination (HR) repairs DNA double-strand breaks (DSBs) in the S and G2 phases of the cell cycle 1 , 2 , 3 . Several HR proteins are preferentially recruited to DSBs at transcriptionally active loci 4 , 5 , 6 , 7 , 8 , 9 , 10 , but how transcription promotes HR is poorly understood. Here we develop an assay to assess the effect of local transcription on HR. Using this assay, we find that transcription stimulates HR to a substantial extent. T...