Introduction: N-Acetyltransferase 2 (NAT2) modifies the bladder cancer risk in Caucasians who have been exposed to aromatic amines. Therefore the NAT2 status and information from the records relevant to the recognition of an occupational disease of the urinary bladder were analysed in a collective of 187 patients. Methods and collective: In 83 of 187 patients assessed between 1991 and 1999, the NAT2 status was determined by phenotyping with the caffeine test which determines the molar ratio of two caffeine metabolites in urine after the subject has drunk two cups of coffee, and/or by genotyping leukocyte DNA with standard methods (PCR/RFLP). In addition, information relevant to the assessment of an occupational disease was taken from the records. Results: The proportion of slow acetylators in the subgroup of 83 patients typed for NAT2 was 67 %. This is higher than reported in recent studies on bladder cancer patients without exposure to aromatic amines. Exposure to potential bladder carcinogens was reported for 73 occupations, most frequently occupations in the chemical industry (25 %) and painters and varnishers (22 %); 68 % of the patients volunteered the information that they had been exposed to aromatic amines. In the entire group of 187 patients, the mean exposure duration was 17.6 years (SD 10.8 years) and the mean latency period was 34.7 years (SD 11.7 years). When first exposed to aromatic amines, 44 % of the group were younger than 20 years of age. Sixty-four percent of the patients were smokers or exsmokers. Conclusion: The determination of the NAT2 status is a useful additional parameter in occupational medical assessment of patients with transitional cell carcinoma, also for cases with only low level aromatic amine exposure.