Sixty-seven bronchoscopic examinations were performed in a busy surgical intensive care unit on 51 patients, and the techniques, morbidity, and outcome were prospectively analyzed to assess the efficacy and safety of the procedure in this particular patient population. General surgical trauma, cardiothoracic, and orthopedic patients were included. Fifty-three (79%) procedures were performed with the flexible instrument, while 14 patients (21%) underwent rigid endoscopy. Forty-six patients were being mechanically ventilated; 30 had endotracheal tubes, and 16 had tracheostomies. Suspected lobar collapse (60%), persistent pulmonary infiltrates (3%), suspected aspiration (21%), and suspicion of airway trauma (12%) were the primary clinical indications for bronchoscopy. No deaths occurred. Complications were seen in 16 per cent of the procedures and 17 per cent of the patients. There were arrhythmias (other than sinus tachycardia) in seven procedures (11%) and one episode each of hypertension, self-limited endobronchial bleeding, mediastinal emphysema, and increased intracranial pressure. Significant improvement was demonstrated for patients with lobar collapse but not for those with mild atelectasis or pulmonary infiltrates on radiographs taken within 24 hours. Overall, 39 patients (58%) improved radiographically, while 38 patients (42%) did not. Differences in arterial PO2 measured before and after bronchoscopy between groups ventilated with an FiO2 of 1.0, and those who were not did not achieve statistical significance (P less than 0.05).