One of the crucial issues of association studies is the selection of markers. One possible approach would be to select tagging SNPs (tSNPs) according the HapMap information. In this study we present the number of tSNPs required for the association analysis of the entire human genome for all available HapMap population samples: CEPH, Nigerian, Chinese and Japanese. For future association studies, it is also important to know how well the tSNP set of one population sample can describe the markers of another population. Therefore, we have calculated the proportion of markers adequately described by tSNPs and how many additional tSNPs we need to describe all markers of another population.