Immigration has been the principal source of population growth in Australia since European settlement began in 1788. As a result, the Australian gene pool has been constantly evolving, particularly over the last 50 years, during which peoples from many European and Asian countries have arrived in large numbers. Three highly polymorphic DNA loci (D1S80, HLA-DQA1, and human THO1) are used to assess the level of diversity among six immigrant subpopulations that compose significant elements in present-day Australia, namely, Asians, Italians, Greeks, Slavs, Middle Easterners, and a "general white" sample. Asian migrants are the most distinctive of the groups at all three loci, possessing the highest frequencies of alleles HLA-DQA1*3 and D1S80*27, *28, and *30, and an exceptionally high frequency of THO1*9. The European-derived groups cluster together separately from Asians, but Greeks are characterized by their frequencies of HLA-DQA1*2 and *4 and THO1*8. Middle Easterners lie on the fringe of the European cluster. When the results of the present study are combined with worldwide data for each of the three DNA markers, these hypervariable loci, especially D1S80 and THO1, are able to differentiate the major groups of humans. The level of population differentiation revealed by RST values for the three DNA markers is similar to or even less than the values recorded for the less polymorphic classical genetic markers. Therefore these three DNA markers are highly suitable for both forensic purposes and the investigation of population relationships.