Pseudomonas cepacia strain AC1100 has been isolated and reported to utilize 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as sole carbon and energy source. Metabolites from the 2,4,5-T degradation pathway were tested for their mutagenicity in the Salmonella reversion bioassay and genotoxicity in the prophage-induction bioassay. The parental compound (2,4,5-T) and three reported metabolites (2,4,5-trichlorophenol, 2,5-dichlorohydroquinone, and 2-chlorosuccinate) were negative with and without metabolic activation in Salmonella typhimurium strains TA98, TA100, TA102, and TA104. Conversely, 2,4,5-T and 2,4,5-trichlorophenol were positive in the prophage-induction bioassay with added S9. 2,4,5-Trichlorophenol was approximately 100-fold more genotoxic than 2,4,5-T 2,5-Dichlorohydroquinone was a weak direct-acting genotoxicant in the assay. In order to determine if strain AC1100 eliminated genotoxicity, 2,4,5-T medium was inoculated and the genotoxicity and the amount of 2,4,5-T remaining were examined over the growth period. As cell numbers increased, the percentage of 2,4,5-T remaining in the medium decreased. The decrease coincided with a decrease in genotoxicity in the prophage-induction bioassay. No mutagenic response was observed in the Salmonella reversion assay.