Abstract: The distribution of 9 red- -cell blood-group systems and ABH secretion was studied on 208 Yaozu testees in Bama Yaozu A utonomous County, Guangxi Zhuang Autonomous Region. In the ABO system, the percentage of phenotype 0 (60.1 %) and gene frequency r (0.7771) are very high, while the A- phenotype percentage (13.0%) and gene frequency p (0.0776) are the lowest ones observed in China. The frequency of s gene in Ss system is found also to be the lowest figure among the populations studied in China up to date. The CDe chromosome frequency (0.8146) is very high while that of cDe (0.0232) is quite low, which tallies with the characteristics of southern ethnic groups in China. In the Kidd system, in contrary to most populations in China, the Jk^a frequcncy of Yaozu (0.5649) is higher than that of Jk^b. The Xg gene frequency (0. 7469) should be considered very high. A nd the distribution of P and Duffy systems of Y aozu has some similarity to those of southern ethnic groups, while those of MN, Diego,Lewis and ABH systems do not show any evident distinguishing feature. The genetic distances and phylogenic tree obtained on the basis of gene frequencies of 15 loci of 9 ethnic groups show that the Y aozu should be included into the Mongoloids of southern--A sia type.

Key words: Red cell blood groups; Gene frequency; Yaozu; Human population genetics; ABH secretion