A clear diagnosis of occupational asthma in hairdressers usually is difficult since standardized tests are lacking. We investigated the potential role of F (E)NO measurements for complementary diagnostic and pathophysiological assertions. Only a few of the work-related respiratory complaints of fifteen examined hairdressers were associated with a significant bronchial obstruction at rest, a non-specific hyperreactivity, a broncho-obstructive reaction in the specific provocation test and/or a type I allergy to work-related agents. In a total of 53 %, at least one of these parameters was pathological and multiple deviations were exceptional. It is remarkable that atopical subjects were underrepresented in the whole group, but represented the majority of those hairdressers who had developed the occupational disease no. 4302. The results of F (E)NO measurements performed for the first time with a group of hairdressers (we found in only 3 subjects increased baseline values, in only 1 subject increased F (E)NO after the exposure test) which diagnostically proved to be helpful to detect allergic and isocyanate asthma are also inconsistent with a substantial airway allergy due to work-related substances. On the other hand, the few atopical hairdressers show a significantly higher disease risk. Hairdressers' respiratory complaints obviously occur mainly due to chemical-irritative stimuli on the bronchial mucosa, especially in atopical subjects. In contrast to our results, by acknowledgment of an occupational disease mostly (in about 66 %) allergizing effects according to occupational disease no. 4301 are accepted.