We report herein the identification of a new HLA-B*51 allele in a Spanish Caucasoid organ donor. The novel allele, designated B*5130, differs from B*51011 by one nucleotide change at position 787 (A to G) in exon 4, leading to an amino acid change from Arg (AGA) to Gly (GGA) at codon 239 in the alpha3 domain. This substitution is present in most classical and nonclassical HLA class I loci (A, C, E, and G) but not in any of the HLA-B alleles reported so far, except for B*7301. Although the frequency of the new variant seems to be low, its existence makes mandatory the analysis of exon 4 before assigning a B*5101 type.