Abstract: The genetic polymorphism of seventh component of human complement (C7) was invest-igated for the first time in China. The gene frequencies of C7 alleles of Han subpopulations were: C7*1- .9144, C7*2- .0668, C7*4- 0.187 for Harbin; C7*1- .9070, C7*2- .0528, C7*4- .U402for Xi'an; C7*1- .9072, C7*2- .0696, C7*4- .0180, C7*3- .0052 for Chengdu; C7*!- .8152, C7*2-.1527, C7*4- .0296, C7*3- .0025 for Guiyang; C7*1- .8821, C7*2- .0849, C7*4-. 0212, C7*3- .0118for Zhangzhou. The results showed that the distribution of C7 in Guiyang Han was some what peculiar, that is, the frequency of C7*1 was lower and that of C7*2 was much higher than thoseof other four populations. According to the present study and previous reports, C7*1 was generally preponderant, and the frequency of C7*2 had its lowest falue in England and ratherhigh in Japan. The Chinese subpopulations had a mid value of C7*2 with exception of Guiyang subpopulation which had the highest frequency. The C7*3 gene was aIso observed in three sou-thern Han subpopulations (Zhangzhou, Chengdu and Guiyang).

Key words: Seventh component of complement; Human genetics; Gene frequency; Han ethnic group