The aim of the present study was to assess respiratory health in professional firefighters. A total of 101 male professional firefighters from Basel, Switzerland, were included in the study. A control group consisting of 735 male subjects of the general population was composed of the Basel sample of the Swiss Study on Air Pollution and Lung Diseases in Adults. All subjects were administered a standardised questionnaire, spirometry, skin-prick tests and bronchial challenge testing to methacholine. Respiratory symptoms at work were more frequent in firefighters compared with the control group, including burning eyes (21 versus 3%), running nose (19 versus 2%), itchy throat (26 versus 3%), cough (28 versus 3%), dyspnoea (7 versus 2%) and headache (25 versus 3%), respectively. Atopy was present in 51% of firefighters compared with 32% in the control group. The odds ratio for hyperreactivity to methacholine was 2.24 (95% confidence interval 1.12-4.48) for firefighters compared with the control group. Firefighters reported more respiratory symptoms at work and suffered more often from atopy compared with the control group. Bronchial hyperreactivity was more pronounced in firefighters, but it was not related to acute exposure or duration of employment. It remains unclear whether these findings were present at recruitment or developed after joining the workforce.