The European Commission requested EFSA to evaluate the efficacy of peroxyacids as an antimicrobial substance applied to poultry carcasses. Particularly, the BIOHAZ panel was asked to assess the efficacy of the peroxyacids on the growth and/or prevalence of some microorganisms and pathogens on poultry carcasses. The efficacy of peroxyacids was difficult to assess because the protocols submitted by the company were not always fully explained. The design of experiments on commercial processing lines did not allow assessment of the efficacy of peroxyacids, only comparison of two different ways of treating visibly contaminated carcasses. In addition the processing conditions did not reflect the conditions and practices in Europe. In the trial on commercial processing lines Salmonella was the only pathogen considered while data on thermophilic Campylobacter spp., which are the most important pathogens of concern in poultry, were not provided. Two experiments were adequately described but they were small laboratory experiments, not adequate to demonstrate the efficacy of peroxyacids under commercial conditions. Decontamination of poultry carcasses is generally intended to reduce the number and/or prevalence of pathogenic microorganisms. However, according to the opinion of Scientific Committee on Veterinary Measure related to Public Health (SCVPH, 2003) and to the European Commission, decontamination should only be used as an additional measure to further reduce the load of pathogenic microorganisms and it must not be used as a substitute for normal good hygienic practice. Moreover, the experimental evaluation of the efficacy of peroxyacids must be under conditions comparable to European industrial processing conditions and practices.