Atopy has emerged as a major determinant of airway inflammation. To examine whether early markers of occupational asthma increase with degree of sensitisation. This study was a prospective follow-up study of apprentices in baking, pastry-cooking and hairdressing during their 2-year apprenticeship. Four visits were conducted to administer a standardised questionnaire, a methacholine challenge test to assess bronchial hyperresponsiveness (BHR) and to measure fractional exhaled nitric oxide (FeNO). Degree of sensitisation was estimated based on the number of positive skin prick tests (SPTs) for 12 common allergens. Mixed-effect models were applied to examine the association between the degree of sensitisation and FeNO levels, BHR and eosinophilic status (more than 3% of cells in nasal lavage fluid). Of the 441 apprentices who agreed to take part in the study, 417 had at least one SPT session providing usable results. Degree of sensitization was related to BHR and FeNO levels. Compared to non-sensitised subjects, FeNO levels were 83% higher (P < 0.01) in highly sensitised subjects and 30% higher (P < 0.01) in weakly sensitised subjects. However, the degree of sensitisation was not predictive of the evolution of these markers. Degree of sensitisation is related to early markers of airway inflammation.