Nine children with bronchopulmonary dysplasia were studied at a mean age of 8.4 years. Persistent respiratory symptoms were common. Pulmonary function tests demonstrated airway obstruction and abnormal blood gas levels in most. In six of eight children results of methacholine challenge tests were positive, indicating bronchial hyperreactivity. Abnormal chest radiographs persisted in eight children. The bronchial hyperreactivity is a likely consequence of airway damage in infancy and is the probable reason for episodic wheezing in the early years of life. Improvement in expiratory flow rates following bronchodilator inhalation suggests that such therapy may improve function in these children.