HCC specimens from high and low AFB1 risk areas in Guangxi showed different frequency of p53 mutational hot-spot, which were 20/35 (57%) and 1/10 by DNA sequencing and 36/52 (69%) and 2/10 by RFLP analysis respectively. Their differences were significant (P<0.01). Mutational points of p53 gene induced by AFB1 mutageu almost exclusively clustered at codon 249 third nucleotide and by the form of G to T transversion only. We call it "AFB1 mutational hot-spot". It turns out to be a significant marker for molecular epidemio-logic survey to decide how many HCC and which individuals are induced by AFB1 mutagen, and if emergence of this marker in HCC is frequent in certain region it indicated that there is heavy contamination by AFB1.