Three different p53 DNA polymorphisms (a 16-bp duplication in intron 3 and BstUI and MspI RFLPs in exon 4 and intron 6, respectively) and haplotype combinations were studied in some major ethnic groups: Caucasians (Swedes), Chinese, Dravidian Indians and African Blacks. Significant ethnic differences in single polymorphisms were found between all groups except for African Blacks-Dravidian Indians, who differed only in their MspI7-16-bp duplication haplotype distribution. Since previous results have shown that p53 alleles are correlated with latitude (degree of insolation), the similarity between these two groups, who are genetically quite distinct, may be due to ecological adaptation to similar climatic conditions. All other major ethnic groups differed significantly from each other with respect to their haplotype distributions; thus, p53 alleles and haplotypes should be very useful as anthropological markers. Asiatic Mongoloid groups appear to be characterized by very low frequencies of the 16-bp duplication and the MspI A1 allele. These mutations have probably been introduced by migration to east Asia from either Europe or Africa, where the highest frequencies were found. The results of this study indicate that p53, besides its role as a tumor suppressor, shows distinct ethnic heterogeneity and may be involved in ecological (climatic) adaptation.