In a two-year randomized controlled study, we studied the effects of bronchodilator treatment on the lung function and the quality of life in patients with mild airflow obstruction. The patients were randomly divided to receive either continuous or symptomatic bronchodilator treatment. Within these treatment groups, they received salbutamol in the first year and ipratropium bromide in the second or vice versa. In addition, the quality of life of the patients was compared to that of the general population. One hundred and forty-four patients completed the study. When compared to the general population, these patients showed a serious impairment in quality of life. No differences between the two drugs were found, but the results indicated that FEV1 decline in the continuously treated group was significantly larger than in the symptomatically treated group. However, this was not reflected in a significant deterioration of the quality of life in the continuous group as measured by means of the Nottingham Health Profile and the Inventory of Subjective Health. Decline in FEV1 showed no correlation with changes in quality of life scores. This may be due to a relatively rapid adjustment of the patients to a decline in FEV1, as a result of which it has no direct effect on the experienced quality of life. Another reason may be that continuous bronchodilation masks the worsening of the disease. This lack of awareness might in turn be caused by the continuous symptom relief of bronchodilators.