The aim of the current study was to describe the incidence of respiratory symptoms and allergic sensitisation and the sequence of events leading to respiratory symptoms among Danish baker apprentices (BA). A total of 114 BA were surveyed over a 20-month period. Questionnaires were completed along with spirometric analysis and skin-prick tests to common and work-related allergens. Bronchial hyperresponsiveness (BHR) was determined at baseline and at the end of the follow-up period. The incidences of work-related rhinitis and asthma-like symptoms were 22.1 and 10.0 cases.100 person-yrs(-1), respectively. At 20 months the cumulative incidence proportion was 40.2 and 20.5% for rhinitis and asthma-like symptoms, respectively. The cumulative incidence of occupational sensitisation was 6.1%. An increased risk of asthma-like symptoms was found in both atopic subjects and in females. In the BA with new onset respiratory symptoms, an increase in BHR from baseline was observed. Forced expiratory volume in one second and forced vital capacity did not change during the follow-up period. No relationship was observed between new sensitisation and new symptoms. In conclusion rhinitis- and asthma-like symptoms were found to develop commonly in Danish baker apprentices. The mechanism by which symptoms arose was perceived to reflect the development of an inflammation rather than the production of a specific immunoglobulin E pathway, as sensitisation to occupational allergens was rarely observed. Hence, respiratory symptoms and allergy may develop through separate pathways.