A seroepidemiological study on HBV infection was carried out in the villages of Changbei, Shanghai, Beihu, Tianjing and Xipu, Taiyuan, July-October 1993. The positivity rates of HBsAg in these villages were 6.4%, 3.4%, 4.8%, respectively. Compared with those in Beihu and Xinpu village, HBsAg carriers in Changbei village had significant fectures as follows: 1. They were much older than those in Beihu and Xipu villages. 2. The positivity rate of male was much greater than that in female. 3. The positivity rate of HBeAg was lower, anti-HBe was higher than those in Beihu and Xipu village. 4. Those of low titre were much more common than those of high titre. A series of analysis indicated that all those festures were related with the large-scale HBV vaccination in adolescents of Changbei village in recent years.