The p53 gene has a polymorphism at codon 72 that presents the arginine or proline genotype, although this polymorphism has been associated with genetically determined susceptibility to lung cancers, the literature has not been consistent with this association. In Chile lung cancer represents the second cause of mortality from cancer. p53 codon 72 polymorphism frequency was studied in a Chilean subpopulation of 133 healthy controls and 111 lung cancer patients. The allelic distribution of the three genotypes (ArgArg, ArgPro, ProPro) in healthy normal controls was 41, 44 and 15%, respectively, which differs slightly from that of lung cancer patients, which was 38, 40 and 22%. A relation between the presence of the Pro allele and lung cancer risk in male smokers was observed. Relative risks were O.R.=2.47 (95% CI: 1.34-4.54) for one single nucleotide polymorphic allele (Pro) and O.R.=3.88 (95% CI: 1.16-13.39) for ProPro genotype.