SNPbrowser Software is free, downloadable software for viewing a genome-wide human genetic variation map, based on single nucleotide polymorphisms (SNPs). It allows researchers to use linkage disequilibrium (LD) map information to select SNPs and other study parameters, and includes links to TaqMan Assays-on-Demand. The software makes it easy to query the physical location of SNPs on chromosomes and linkage disequilibrium maps, view putative haplotype block boundaries and assess the likely statistical significance of a study. The genetic variation map is the result of over 40 million genotypes generated through the validation of more than 150,000 SNP genotyping assays. The selected SNPs were validated by individually genotyping 180 DNA samples from African-American, Caucasian, Chinese and Japanese individuals.