Human hepatocellular carcinomas from patients in Britain, an area of low prevalence of hepatocellular carcinoma and low dietary exposure to aflatoxin B,, were analyzed for mutations in the p53 tumorsuppressor gene. Abnormalities in the pS3 gene were detected in 2 of 19 hepatocellular carcinomas by polymerase chain reaction-single-stranded conformation polymorphism. Direct sequencing of the evolutionarily conserved regions of pS3 (exons 6.6.7 and 81, where mutations have been commonly found in a variety of tumors, confirmed that only two hepatocellular carcinomas had mutations in pS3, one a 6-bp deletion of codons 158 and 159 (exon 5 ) and the other a G to A transition at codon 286 (exon 8). No mutations were found in any hepatocellular carcinoma in exons 6 and 7; in particular all tumors had wild-type sequence at codon 249, which has been reported to be a mutational hot spot in the pS3 gene in hepatocellular carcinomas from high incidence areas such as China and southern Africa. Abnormalities in p53 expression were examined by immunohistochemistry and found in 1 of the 19 hepatocellular carcinomas. These findings show that pS3 mutations are infrequently involved in the malignant transformation of hepatocytes in an area of low hepatocellular carcinoma prevalence. They support the suggestion of a possible link between dietary exposure to &atoxin and selective G to T mutations at codon 249 of the pS3 gene. Our observations also indicate that hepatitis B virus infection alone, present in six of the hepatocellular carcinomas examined, does not account for the specificity for codon 249 mutations reported from endemic areas.