Abstract: An investigation was carried out on 11598 cases of marriage in Dai, Hani, Yi, Jino, Lahu, Kucong, Hur and Han ethnic groups of Yunnan Province in 1985. The findings are as follows:
1. The difference of consanguineous n1arriage percentage between the urban and rural regions, as well as between ethnic. groups, was significant.
2. The consanguineous marriage percentage in all nine ethnic groups investigated was higher than that of the same groups in developed regions of China.
3. The marriages between first cousins and 1? consins accounted for 84.7% of the total number of consanguineous marriage.
4. The average inbreeding coefficient (AIC) of nine ethnic groups investigated was higher phan that of the same groups in developed areas. Among them the AlC of Kucong (0.018579) was the highest in the country. Even the AIC of Han (0.001935), which showed the lowest value among nine ethnic groups, appeared to be higher than that of Han in Beijing Shanghai and Yichang City of Hubei Province.

Key words: Consanguineous marriage