<i>Background:</i> The aim of this study was to determine the prevalence of possible occupational asthma (OA) in hairdressers. <i>Methods:</i> A telephone questionnaire (Q1) was administered to 1,334 individuals from a total of 1,875 hairdressers working in hair salons for women in Barcelona (response rate 71%) to identify those with respiratory symptoms. Multiple correspondence analysis showed 5 specific questions for assessing symptoms of asthma. Individuals who gave a positive response to 1 of these questions (n = 251) were given a second validated questionnaire (Q2) to identify those with suspected OA. OA was defined according to a classification tree based on the response to queries on nasal itching, daily symptoms throughout the week at work, nasal secretions, voice loss, wheezing, and sputum production as reported previously. Moreover, we calculated the prevalence of OA according to the conventional criteria of improvement and/or worsening of symptoms in relation to exposure at work and during off-work time on weekends and during vacations. <i>Results:</i> Asthma was present in 9.5% of hairdressers. From Q2 data, 72 were classified as having possible OA, yielding a prevalence of OA from 5.4 (72/1,334) to 7.8% according to the classification tree previously described. A prevalence from 4.6 (62/1,334) to 6.7% was obtained using conventional criteria. Rhinitis or dermatitis (OR 7.80), as well as exacerbation of symptoms at work and persistence of symptoms on weekends (OR 2.99) were associated with the development of OA. <i>Conclusions:</i> Hairdressing employment can induce asthma. Episodes of rhinitis or dermatitis seem to be risk factors for the development of OA in this population.