The authors report the results of a sample survey made in January 1985 in a Northern Cameroon Division following the observation of a very high mortality rate by serious jaundice in 1983 and 1984. Within a representative population sample of 395 persons of more than 4 years old, they observed that: 100 were HBs antigen carriers (detected by ELISA), 25.3% +/- 5.5%, 19 were HBe antigen carriers (RIA), 4.8% +/- 2.4%, and 202 were HBs antigen or HBs antibody carriers: 51.1% +/- 6.5%, There was only one carrier of delta antigen. There is no difference in HBs antigen bearing according to sex or age, but HBe antigen appears to be more frequent among young people.