Evidence for a genetic resistance to scrapie has been observed in different experiments conducted in the UK since the sixties, in particular the 'Sip' gene (Scrapie Incubation Period). In 1991, the relationship between the PrP gene polymorphism and the incidence of natural scrapie in several breeds was described. From 1990 to 1996, different studies showed that three codons of the gene have an action on the susceptibility to natural scrapie. The analysis of an epidemic in a French experimental farm detailed the level of susceptibility of the alleles and genotypes. In France, actions started in 1995 in dairy sheep breeds and in 1999 in meat sheep, through the survey of the frequencies of alleles and genotypes of the PrP gene in 25 breeds. In meat sheep, a few breed societies started a selection programme in 2000. In 2002 a large national programme concerning all the French breeds started.