Arylamines are known bladder carcinogens deriving from tobacco smoke and environmental pollution. Arylamines are metabolised by NAT1 and NAT2 polymorphic enzymes in reactions of carcinogen activation and detoxification. We analysed genetic polymorphisms in both NAT1 and NAT2 genes in 56 bladder cancer patients and 320 healthy patients. Peripheral blood lymphocytes were collected from each subject and genotyped for NAT1 (six alleles) and NAT2 (four alleles) by PCR-RFLP. A weak association between NAT1 and NAT2 genotypes and bladder cancer risk was found when the genotypes were estimated separately (odds ratio OR 1.2, 95%CI 0.7-2.0, and OR 1.3, 95%CI 0.7-1.9, respectively). Almost all NAT1 genotypes possessing at least one "risk" *10 allele were more frequent in the bladder cancer group than in the control group. There was also an increased frequency of "risk" genotypes along with increased cigarette smoking in bladder cancer patients. The coincidence of NAT1-fast/NAT2-slow appears as a potential risk factor for urinary bladder cancer (OR 1.5, 0.8-3.0), as compared with the other genotype combinations.