Relatively little is known about the consequences of asthma for patients' work ability. In particular, the relationship between asthma and construction work has not been studied previously. The aim of this study was to determine how asthma affects construction workers' work ability and quality of life, and the most important conditions that cause respiratory symptoms in construction work. A questionnaire was sent to all construction workers examined in the pulmonary clinic of Tampere University Hospital between 1991 and 1995 who were diagnosed as having 'asthma bronchiale' (n = 104). In addition, 206 non-asthmatic construction workers were recruited from the register of the local trade union. Altogether, 73% of the asthmatic construction workers and 70% of the controls completed the questionnaire. Of the asthmatics, 48% were retired, whereas only 24% of the controls were receiving a pension. The asthmatics evaluated their work ability and general health as significantly worse than did the controls. The asthmatics had more limitations in their work and everyday life than the controls. Asthmatic construction workers had often changed work tasks and also occupation because of their illness. Building renovation, cleaning and insulation with mineral fibre materials were the most common causes of respiratory symptoms in the workplace, among both the asthmatics and the controls. Cold air, physical exercise and all types of dust and smoke caused the asthmatics to experience symptoms. It was concluded that asthma limits the work and everyday life of construction workers. Exposure to dusty, non-sensitizing agents is associated with asthmatic symptoms among construction workers.