To determine the diagnostic and therapeutic usefulness as well as safety of flexible fiberoptic bronchoscopy (FFB) in patients admitted to the critical-care unit (CCU), we conducted a review of all such procedures done in our CCU from 1985 to 1988. A total of 129 patients underwent 198 FFB, of which 76% were in mechanically ventilated patients. FFB was done for diagnostic purposes in 87, for therapeutic purposes in 93, and for both reasons in 18. Of the 71 diagnostic FFB performed for cultures, 27 (38%) were positive but only 18 (25%) influenced patient management. An additional 25 FFB were helpful in making therapeutic decisions even though the cultures were negative. Ten of 13 FFB performed for evaluation of airways and 1 of 3 done for hemoptysis were helpful. Of the 90 FFB done because of retained secretions, 37 (41%) showed mucous plugs or significant secretions, but clinical improvement was noted in only 17 (19%). Overall, FFB contributed substantially to patient management in 82 of the 198 procedures (41%). Seven patients had transient complications, but no deaths occurred. We conclude that FFB is safe and can be helpful in the CCU setting.