HLA-B typing of approximately 1 262 individuals from a study of 372 simplex families with multiple sclerosis has led to the identification of two new alleles (HLA-B*4422 and HLA-B*4704). Sequencing confirmed that both of these new alleles represent novel combinations of previously described sequence motifs, reinforcing the notion that recombination and/or gene conversion-like events play an important role in generating HLA allelic diversity. The identification of these new alleles brings the total number of HLA-B alleles to 465.