Operon fusion and S1 nuclease mapping have been employed to locate a putative uvrC promoter, which is situated approximately 200 bp ahead of the uvrC structural gene. The promoter sustains transcription towards the uvrC coding sequence and is inducible by DNA damaging agents. The inducibility is dependent on the Escherichia coli LexA and RecA functions. Examination of the DNA sequence in the promoter region reveals the presence of a sequence similar to the consensus of a SOS box. In contrast to the related uvrA and uvrB genes, uvrC gene expression is characterized by a delayed onset of induction after DNA damaging treatment. Furthermore, no induction is observed with nalidixic acid.