Bilateral cultures of bronchoalveolar lavage fluid were obtained from eight children with unilateral lobar pneumonia. In four patients bacterial pathogens were not isolated from lavage of the radiologically normal side but were subsequently cultured from the consolidated segment. This pattern helped to exclude contamination by oropharyngeal flora of bronchoalveolar lavage fluid. Bilateral bronchoalveolar lavage may help in the interpretation of lower respiratory tract cultures obtained by fiberoptic bronchoscopy.