To test a method of obtaining specimens for microbiologic culture from the lower respiratory tract, we bronchoscoped 25 otherwise normal subjects with and without experimental rhinovirus infections and collected specimens for bacterial culture with a brush housed in a plugged double catheter apparatus. Fifty-two specimens of the lower respiratory tract were obtained from the 25 subjects; nasopharyngeal swabs were also obtained from each subject prior to bronchoscopy. Specimens obtained from the lower respiratory tract were positive for bacteria in 21 (84%) of 25 subjects and at 38 (73%) of 52 sites. The frequency of obtaining positive bacterial cultures was similar in volunteers with (69%) or without (90%) rhinovirus infection. Oropharyngeal contamination of bronchial specimens was minimized by administering atropine and by bronchoscoping subjects in the supine or Trendelenburg position. These data indicate that the plugged double catheter brush system does not consistently yield specimens that are free of bacterial contamination from the oropharynx.