A specific, non-synonymous SNP in the Prnp gene encoding the bovine prion protein affects the susceptibility of bovine animals to bovine spongiform encephalopathy (BSE). Depending on the number of octapeptide repeat units present in the Prnp gene, the position of the SNP is either nucleotide 631 of exon 3 (codon 211) when the Prnp gene comprises six octapeptide repeat region sequences, nucleotide 607 of exon 3 (codon 203) when the Prnp gene comprises five octapeptide repeat region sequences, or nucleotide 655 of exon 3 (codon 219) when the Prnp gene comprises seven octapeptide repeat region sequences. Alleles of the bovine Prnp wherein the SNP at these positions is lysine (K) at the corresponding amino acids (i.e., 211, 203 or 219) in the bovine prion protein are all indicative of increased susceptibility to BSE in comparison to alleles which encode glutamic acid (E) at the same position. This SNP may be used as a marker for selecting bovines susceptible to BSE for disposal and/or removal from breeding, the human food and animal feed supplies.