Background: The aim of this study was to investigate a possible association of the CYP1A1 Ile462Val and GSTM1 null polymorphisms with the risk of developing bladder cancer in a Turkish population. Patients and Methods: The study constituted 176 patients with bladder cancer and 97 healthy individuals. Evaluation of CYP1A1 Ile462Val gene polymorphism was performed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). GSTM1 null gene polymorphism was exclusively determined by PCR. Our results were examined by statistical analyses. Results: There were no significant differences in CYP1A1 genotype frequencies between patients and controls. Furthermore, the frequency of GSTM1 null genotype was higher in patients compared to controls, but it did not reach significance (p=0.622 chi(2)=0.243 OR=0.94 95% CI=0.75-1.18). Significance was discovered in combined analysis of CYP1A1 and GSTM1 genotypes. In the present study, GSTM1 null genotype with CYP1A1 Ile/Ile genotype combination was significantly more frequent in the patient group than in controls (p=0,04, chi(2)=4.217). At the same time, possessing both GSTM1 null genotype and CYP1A1 Val variants (Ile/Val+Val/Val) were significantly higher in control group than in patients (p=0.017, chi(2)=5.468). When the pathological tumor grades were assessed, the frequency of CYP1A1 Val mutant variant with GSTM1 null genotype combination was higher in patients with medium and high-grade tumors than in those with low-grade tumors (p=0.06, chi(2)=3.527, OR=1.36 95% CI=1.03-1.78). Conclusion: We suggest that the CYP1A1 Ile/lle genotype with GSTM1 null genotype combination may contribute to the development of bladder cancer in this Turkish population.