Several studies investigating associations between prion protein (PrP) genotypes and performance traits in several sheep breeds have recently been published. Most of these studies have failed to give conclusive results due to small numbers of animals used or a potential genotyping bias as those animals selected for PrP genotyping were chosen based on their performance (e.g. De Vries et al., 2005). Polymorphisms of the PrP gene has been linked with susceptibility to scrapie with the ARR allele generally associated with resistance and the VRQ with susceptibility. This study investigates the associations with PrP genotype for a wide range of lamb performance traits in experimental flocks of Scottish Blackface in which all animals have been PrP genotyped.