To investigate mechanisms causing p53 mutations in lung cancer cases, relations between p53 gene mutations and aetiological factors such as smoking history or family history of cancers cases. The contribution of genotypes related to carcinogen metabolism (CYP1A1 and GSTM1) was also analysed. p53 mutations were observed in 13 cases (37.5%). Seven (53.8%) of the 13 patients with p53 mutation compared with five (22.7%) of 22 patients without had a family history of cancer. However, there was no significant relation between p53 mutation or family history of cancer and CYP1A1 or GSTM1 genotypes. In conclusion, p53 mutation might be associated with the inherited characteristics that result in familial aggregation of lung cancer; however, this association was not explained by genotypes of enzymes related to carcinogen metabolisms.