The prevalence of seven point mutations on the polymorphic NAT2 gene was studied in DNA from 108 patients with histologically proved bronchogenic carcinoma and 243 healthy controls. By means of a mutation-specific polymerase chain reaction analysis, the wild-type and fourteen mutant allelic variants of the NAT2 gene were identified. The prevalence for the poor acetylator genotypes in patients and control subjects were similar, however the frequency of mutant alleles was higher in patients with lung cancer. This was attributable to an increase in the prevalence of the allelic variants 590A and 341C + 481T + 803G among patients (p < 0.05 and 0.06, respectively). These allelic variants were at increased frequency in patients with adenocarcinoma, squamous cell or small cell lung cancer. Subjects poor acetylators that are homozygous for the allelic variant 341C + 481T + 803G seem to be at increased risk to develop lung cancer (odds ratio; 95% CI = 1.75; 0.99-3.12). We conclude that the acetylator status is not a major factor in lung cancer risk, however the presence of the 341C + 481T + 803G and the 590A alleles of the polymorphic NAT2 gene may be a secondary risk factor for the development of lung cancer.