Forced oscillometry was used to investigate whether lung injury due to bronchopulmonary dysplasia in early life caused abnormalities in bronchial calibre or an increase in bronchial responsiveness to histamine at school age. Results were compared with data obtained from healthy children born prematurely and from healthy children born at term. There was a mild increase in frequency dependence of total respiratory resistance in children who suffered from lung injury in early life, which indicates uneven ventilation in peripheral airways. Bronchial responsiveness to histamine in these subjects was normal. No abnormalities were found in the control group. We conclude that lung injury in early life may cause residual abnormalities of peripheral airways. This does not happen in premature babies who do not have respiratory problems in the neonatal period.