The human genome is 99.9% identical between human beings. The remaining 0.1% of difference constitutes the source of inherited disease. Most of this variation is comprised of single-nucleotide polymorphisms (SNPs), or single-base differences in the genome. By examining associations between SNPs and disease, researchers hope to decipher the genetic underpinnings of disease. Most SNPs have been examined with case-control studies using the "candidate gene approach" in which a single SNP is tested for association with disease. Unfortunately, associations have generally been weak. Multigenic SNP analysis in which hundreds or thousands of SNPs are examined in relation to disease will probably be required to unveil strong, clinically useful genetic associations. Current technological breakthroughs such as sequencing of the human genome and progress in high-throughput SNP analysis predict that that SNPs will have a tremendous impact on both clinical medicine and biomedical research in the near future.