Polymorphisms in glutathione S-transferases (GSTs) may predispose to lung cancer through deficient detoxification of carcinogenic or toxic constituents in cigarette smoke, although previous results have been conflicting. Three GST polymorphisms (GSTM1, GSTT1 and GSTP1) were determined among 86 male patients with lung carcinomas and 88 healthy male subjects. We found no significant increase in the risk of lung cancer for any genotypes for the nulled GSTM1 [odds ratio (OR)=2.0; 95% confidence interval (95% CI)= 0.8-5.3], the nulled GSTT1 (OR=2.0; 95% CI=0.8- 5.1) or the mutated (the presence of a Val-105 allele) GSTP1 (OR=0.96; 95% CI=0.4-5.5). The GST polymorphisms alone may thus not be associated with susceptibility to lung carcinogenesis in male Japanese. However, individuals with a concurrent lack of GSTM1 and GSTT1 had a significantly increased risk (OR=2.7; 95% CI=1.0-7.4) when compared with those having at least one of these genes. No other combinations were associated with lung cancer risk. These results suggest that there may be carcinogenic intermediates in cigarette smoke that are substrates for both GSTM1 and GSTT1 enzymes and that lung cancer risk is increased for individuals who are doubly deleted at GSTM1 and GSTT1 gene loci. Additional large studies are needed to confirm this observation.