The scrapie is a neuro-degenerative disease that affects goats and sheep. In sheeps, the genetype of the gene PrP determines the animals' highest and lowest resistance of suffering from the disease. This different resistance is specially influenced by the codons 136, 154, and 171. The CERSYRA of Valdepeñas has initiated the genetic analysis of these three polymorphic positions in the PrP gene in the selection and breeding program of animals belonging to the Manchega race (ESROM) of sheep in order to design, once it is known the general situation of the two varieties of this race, White and Black, the most adequate strategies to improve the genetic resistance to this disease.