The distributions of haplotype diversity across the whole genome among 10 US beef cattle breeds were constructed. In most chromosomes for all the breeds, consistent low haplotype diversity were observed in some specific regions, 55% of which was found to match the positions of reported gene duplications. Further work is required to determine whether the low haplotype diversity is real, or a result of problems in sequencing which have limited our ability to identify informative markers in those regions. Haplotype diversity will be the subject of ongoing work to identify haplotypes that are under-represented as homozygotes, to fine-map regions with major gene effects, and to fit haplotype rather than SNP models for genomic prediction.