Y-chromosome polymorphisms are powerful tools in delineating the genetic structure of human populations. A large number of populations in China have been studied in the last several years and 17 Y-chromosome single nucleotide polymorphism (SNP) haplotypes have been found in them, some of which are specific to East Asians. Major ethnic groups tend to have their own characteristic profiles reflected by their respective Y haplotype distribution. Kra–Dai, an ethnic group dispersed from Assam to Taiwan, is a relative homogeneous group, although some resemblance between Kra–Dai and Austronesian groups, especially Taiwanese aborigines, are also noticeable. The most frequent haplogroup among the Kra–Dai-speaking peoples is haplogroup O2a followed by O1a and O1a1.