RFLPs of TCR beta and gamma genes have been analyzed in chronic HBV carriers of three different ethnic populations to determine if there is an association of TCR allotypes with the development of chronic hepatitis B. The RFLPs of TCR beta and gamma genes were defined respectively by BglII and PvuII genomic fragments on Southern blots. These methods allow allotype assignment. The distribution of TCR beta alleles showed ethnic variation, with one allele significantly decreased in Australian Aborigines, but there was no association with chronic hepatitis B. The distribution of TCR gamma alleles did not show ethnic variation. However, a significant frequency decrease of one allele occurred in Aboriginal HBV carriers, suggesting the possibility of involvement of TCR gamma allotypes in the development of the chronic HBV carrier state in Australian Aborigines.