Abstract: At the end of 1980, an opportunity was afforded for us to make anthropological surveys of the Hainan islanders. Altogether 1268 individuals, consisting of Li, Han, Hui, Miao, tribes and Lingao people in Hainan, and one group of Han in Shucheng County, Anwhei Province, were determined for ABO, MN blood groups. Data of ABO, MN blood groups of the aboriginal groups mentioned above are presented here.
It is shown by the distribution of ABO blood groups that there exist definite differences between the aboriginal groups in Hainan and at the same time shown by X2 test according to Hardy-Weinberg's law. However, all these groups are in a condition of genetic equilibrium. We may hence infer than these aboriginal groups are under the condition of reproductive isolation in certain degree from each other though having lived together in Hainan for a long time. The distribution of MN blood types of all the groups in this study may properly be divided into two types: M gene frequencies higher for the groups in Hainan, and lower for the Han group in Shueheng.
Blood groups of other peoples from the data previously published by others have been utilized for comparison.
ABO blood groups. A gene frequency of the Han in Hainan is obviously lower than that of both the Northern and the Southern Han series. Both p and q of the Liangao people are significantly lower than that of the two Han series, the Northern and the Southern, and very near to the Zhuang people in the Guangxi Zhuang Autonomous Region and the Paiwan peopl ein Taiwan province. It is implied in this connexion that the Lingao people has a close genetic relation with the Zhuang people. Li group, the major object in this study, is very near to both Zhongjia in Guizhou Province and Tai in Bangkok, Siam, in terms of ABO blood groups. Much work done by other authors on the ethnological aspects has led to the conclusion that Li group has a close racial relation with Zhongjia and Tai. This confirmed by our results of the blood grouping.
MN blood types. There are higher M gene frequencies in South Asia and Java. Districts of South China including Hainan Island have higher M gene frequencies. It is supposed from the high M gene frequencies that there may be close racial relation between peoples of South China and South Asia.

Key words: Hainan Island; Li tribe; Lingao people; ABO blood groups; MN