The response of salbutamol (Ventolin, Glaxo), topically administered from a metered dose inhaler (MDI) through a new baby-spacer-device (Babyhaler, Glaxo) was studied in 14 infants (8 wheezy infants, 3 infants with cystic fibrosis and 3 infants after respiratory distress syndrome), age 2.9-18.8 months. Changes in thoracic gas volume (TGV) as an estimate of pulmonary hyperinflation and changes in airway conductance (Gaw) as an estimate of bronchial obstruction were assessed by whole-body plethysmography. After baseline measurements, 1 puff of 100-mu-g salbutamol was given repeatedly at 5 min intervals until 600-mu-g have been inhaled and TGV and Gaw were measured after each inhalation at 5, 10, 15, 20, 25 and 30 min. Significant improvement in lung function was achieved in 57.1% of infants after 400-mu-g and in 92.9% of infants after 600-mu-g salbutamol. The study shows usefulness of bronchodilator treatment in infants with bronchopulmonary disease by a system with a MDI and baby-spacer-device. However a special dose-time relationship must be respected.