采用限制性片段长度多态性（ＲＦＬＰ）方法对北京（６０例）和湖北（５８例）地区随机人群的补体Ｃ４基因的长度进行检测。结果：湖北人群Ｃ４短基因的分布频率较北京人群高，其表型频率分别为 ７９． ３１％、６１．４４％，基因频率分别为５１．７２％、３７．５０％，差异均有显著意义（均为Ｐ＜０．０５），而且Ｃ４短基因在上述二个人群中的分布均符合Ｈａｒｄｇ－Ｗｅｎｂｅｒｇ平衡。结果表明，湖北人群Ｃ４短基因的频率高于北京人群。这种由于逆转录病毒序列的插入所致的Ｃ４基因长度的变化为研究某些疾病的遗传易感性提供了线索。 The length of complement C4 gene in random populations of Beijing (60 cases) and Hubei (58 cases) was detected by restriction fragment length polymorphism (RFLP). Results: The distribution frequency of C4 short genes in Hubei population was higher than that of Beijing population, and their phenotypic frequencies were 79. 31% and 61.44% respectively. The gene frequencies were 51.72% and 37.50%, respectively (all P <0.05), and the distribution of C4 short allele in the above two groups Meets Hardg-Wenberg balance. The results showed that the frequency of C4 short gene in Hubei was higher than that in Beijing. This change in C4 gene length due to the insertion of retroviral sequences provides a clue for studying the genetic susceptibility of certain diseases.