Human HLA genes exhibit extreme polymorphism, the extent of which is emphasised by the identification of an ever increasing number of new alleles by DNA-based typing strategies. Here we describe a novel allele, belonging to the HLA-B*15 group, which was identified in an African patient awaiting a bone marrow transplant This individual was shown to exhibit two HLA-B alleles, B*5301 and a new allele which has been named B*1555. B*1555 differs from B*1531 in exon 3 by a single nucleotide substitution. This substitution results in a change in the amino acid residue at position 97, which is located within the beta-pleated sheet region of the HLA molecule.