Flexible fibre-optic bronchoscopy was performed under sedation in 24 children with cystic fibrosis. In eight cases bronchoscopy was carried out as a therapeutic procedure. Most children were subjectively improved, but objective evidence of change was minimal. Useful information was obtained in 9/16 children who underwent the procedure for diagnostic purposes. Information included sensitive identification of organisms responsible for lower respiratory symptoms in non-expectorating cases and identification of unsuspected gastro-oesophageal reflux.