The recently described red cell acid phosphatase phenotypes were studied in a population of 260 Australian Whites and 4 groups of New Guinea natives totalling 787. The results demonstrate differences in Pa, Pb and Pc frequencies between the Australian Whites and the New Guinea natives and between most of the individual New Guinea native groups. All population samples in this study conform to the Hardy-Weinberg equilibrium. No association was observed between acid phosphatase types and ABO-, MNS- and Rh-blood groups.