A questionnaire was sent to 1,041 owners of fiberoptic bronchoscopes requesting data about complications of bronchoscopic examination; 323 (31 percent) of the questionnaires were returned. From approximately 48,000 procedures, ten deaths were reported and are described. Information about two additional deaths not obtained from data on the questionnaires is also included. All patients who died had either myocardial disease, severe chronic pulmonary disease, serious pneumonia, or cancer. Two deaths were associated with evidence on necropsy of fresh myocardial infarctions that had been unsuspected prior to the procedure. Two deaths occurred after administration of local anesthesia prior to bronchoscopic examination. Two were patients who previously had slowly hemorrhaging tumors that hemorrhaged massively following, respectively, forceps biopsy and saline lavage. Four brushes broke off in bronchi. Ten cardiac arrests and 41 life-threatening reactions to anesthesia also occurred.