Flexible fiberoptic bronchoscopy was evaluated in 71 procedures in 55 patients. Two-thirds of these procedures were carried out in patients with ongoing mechanical ventilation as their respiratory failure contraindicated rigid bronchoscopy. A wide variety of important diagnostic information was obtained. FFB caused no mortality or serious complications. Transient tachycardia occurred in several patients, cardiac arrhythmia in two and mediastinal emphysema in one patient. Retained secretions and atelectasis were the indications for 53 FFBs; 43 (81%) of these procedures were successful in improving aeration as evaluated with radiography.