The inception of the International Haplotype Map Project (http://www.hapmap.org/) and completion of stages I and II of this project has led to the production and public dissemination of a map of patterns of human genetic diversity in four populations; Japanese from Tokyo, Central Europeans from Utah, Han Chinese and Yorubans from Nigeria. These data present unprecedented opportunities in human genetics; they provide invaluable information on human evolutionary history and for the first time present a roadmap for mapping genetic variability that underlies complex traits. The invention and application of ultra-high throughput genotyping technologies is beginning to realize this latter goal, even in the early days of this effort the HapMap Project is proving worth the time and resources invested thus far.