Criteria for selecting lung donors include normal chest X-ray and adequate gas exchange, but normal bronchoscopy is not always required. Thus, we conducted a prospective study of fiberoptic bronchoscopy in 72 brain-dead donors scheduled for multiple organ procurement. Chest X-ray was considered normal in 37 donors (51%), and PaO2 was > 400 mm Hg with an FIO2 of 100% in 34 donors (47%). Fiberoptic bronchoscopy was normal in only 24 donors (33%). In the remaining 48 donors, inhalation of gastric contents (n = 26) or blood (n = 17), pulmonary contusion (n = 5), or purulent bronchial secretions (n = 4) were noted. In the 26 donors with normal chest X-ray and PaO2 > 400 mm Hg with FIO2 of 100%, bronchoscopy was abnormal in 10 donors (38%). In 33 donors, arteriovenous difference in oxygen content (2.4 +/- 0.8 ml O2/100 ml), and pulmonary shunt (0.30 +/- 0.11, range 0.13-0.49) were measured. In the 15 donors with PaO2 > 400 mm Hg, pulmonary shunt was 0.23 +/- 0.07 (range 0.13-0.35). Our study suggests that chest X-ray and arterial blood gas analysis are not sufficient, and that fiberoptic bronchoscopy should be routinely performed to select potential lung donors. Even in brain-dead donors, only the measurement of pulmonary shunt can precisely assess pulmonary gas exchange.