Three different p53 polymorphisms (a codon 72 BstUI RFLP, a 16-bp duplication in intron 3 and an MspI RFLP in intron 6) and haplotype combinations were studied in three northern European populations, viz. Finns, Swedes and Swedish Saamis. Significant ethnic differences were found in the codon 72 and 16-bp polymorphisms. The three polymorphisms were in strong linkage disequilibria, all of which were highly significant (p < 1 x 10(-18)), and ethnic differences with respect to linkage disequilibria were observed. Estimates of the frequencies of extended haplotypes showed that the most common ('wild-type') haplotype in the three populations was 2-1-2, viz, the codon 72 Arg allele linked to absence of the 16-bp duplication and presence of the MspI site. There were two additional common haplotypes, 1-1-2 and 1-2-1, and five rare haplotypes with a combined frequency of about 0.03. The present results indicate that extended haplotypes would be more informative in studies of population differences and associations between p53 germline mutations and cancer.