Nucleic acid-based methods for allele identification have revealed more than 470 polymorphic variants at the HLA-B locus. Screening of potential bone marrow donors with sequence specific primer polymerase chain reactions and sequence specific oligonucleotide probe hybridization assays revealed apparent variants within the B*58, *44, *15, and *48 allele groups. DNA sequencing of cloned DNA identified the new alleles B*5804, B*4418, and B*1558 within these groups and observed new sequence information for the previously reported allele B*4805. These findings further extend our knowledge of the substantial genetic variation present at the HLA-B locus within human populations.