The present study was conducted (1) to examine whether the GSTT1- and GSTM1-null genotypes are risk factors for bladder cancer, and (2) to study possible association of tobacco usage and age strata with genotype of these patients. This case control study was undertaken over a period of 19 months and included 106 bladder cancer patients and 182 controls; both patients and controls originated from northern part of India. The GSTT1 and GSTM1 genotypes were identified by multiplex PCR in peripheral blood DNA samples. Genotype frequencies among patients and controls were assessed and the association of the genotypes with smoking habits and gender of the patients were statistically determined by the chi(2) test. Frequencies of null genotypes in GSTT1 and GSTM1, were 16% (29/182) and 30% (54/182), respectively, in control individuals. The frequencies of GSTT1- and GSTM1-null genotypes in bladder cancer patients were 26% (28/106) and 40% (42/106), respectively. In conclusion, our study demonstrated that the null genotypes of GSTT1 and GSTM1 were substantially at higher risk for bladder carcinoma compared to the normal healthy controls. The GSTT1- and GSTM1-null genotypes did not show significant association with tobacco usage in bladder cancer patients. However, the null genotypes were statistically significant in female relative to male bladder cancer patients.