The acute effect on lung function of nebulized salbutamol and saline (placebo) has been investigated in preterm infants at follow-up. Twenty two premature infants, median gestational age 29 weeks (range 26-32 weeks) and birthweight 1,264 g (720-1,800 g), were studied at a median postnatal age of 7 months (range 6-9 months). Nine of the infants had recurrent respiratory symptoms; they coughed and/or wheezed at least 3 days per week for the previous 4 weeks. The remaining 13 infants were free from recurrent or persistent respiratory symptoms. Thoracic gas volume (TGV) and airways resistance (Raw) were measured and specific airway conductance sGaw calculated before and 10 min after salbutamol and normal saline given via a nebulizer. Amongst the symptomatic infants administration of nebulized salbutamol was associated with a median reduction in Raw of 25% (p less than 0.01) and also a significant improvement in sGaw (p less than 0.01). In the asymptomatic infants neither Raw nor sGaw changed significantly. Nebulized saline caused no significant change in lung mechanics in either the symptomatic or asymptomatic infants. We conclude that nebulized salbutamol is an effective bronchodilator for symptomatic preterm infants less than one year of age.