Escherichia coli react to ultraviolet radiation by activating a cellular response against genotoxic stress known as SOS response. In this paper, the importance of different gene products involved in DNA repair to both survival and SOS activation in E. coli strains exposed to ultraviolet B radiation was evaluated. For this purpose, we determined cell survival through the plate counting method in E. coli strains carrying uvrA, oxyR, recO, recN, recJ, exoX, recB, recD, fpg and xonA mutations and in the wild type strain. These strains also contain the genetic sulA