The identification of the novel allele HLA-B*4417, which was found in a blood donor of Caucasian origin, is described. In the sequence analysis the new allele differs from B*4402 by three nucleotides in exon 3. At the protein level, the new allele has two residue differences compared to B*4402. Due to substantial differences with other B*44 variants a possible mismatch may impair clinical outcome of bone marrow transplantation.