Abstract: In 1986 the Aboriginal community in Western Australia was identified as a high-risk group for hepatitis B virus infection. An immunization programme was commenced in 1988 but concerns were expressed about horizontal transmission, especially in schools, to the low-risk Caucasian group and whether they should also be included in the vaccination programme. To estimate the extent of this occurrence, a survey of schoolchildren from two district high schools in Broome and Derby in the Kimberley Region of Western Australia was carried out in March 1989. A total of 607 students aged 4 to 19 years were included in the study. None of the 300 Caucasian students had any serological markers of hepatitis B virus infection (95% confidence interval (CI) upper limit, 1.3%). Eighteen children were found to be seropositive for hepatitis B surface antigen (HBsAg); 17 were Aboriginal and one Asian. In addition, 61 Aboriginal students and one Asian had hepatitis B surface antibody (antiHBs). The hepatitis B virus infection rate in these Aboriginal children is 28.2% (95% CI, 23.2%-33.7%) with a carrier rate of 6.1% (95% CI, 3.9%-9.6%). This study demonstrates that Caucasian students have a very low risk of infection with hepatitis B virus in this community, and there is therefore no need to extend the hepatitis B vaccination programme beyond the already identified high-risk groups.