Pulmonary infections due to anaerobic bacteria usually occur in children prone to aspiration. The source of the anaerobic bacteria is the oropharyngeal bacterial flora, where these organisms outnumber aerobic and facultative organisms in a 10:1 ratio. The most common lower respiratory tract infections where anaerobic bacteria are recovered mixed with aerobic organisms are aspiration pneumonia, lung abscess, and empyema. The predominant isolated anaerobic bacteria are Peptostreptococcus, Fusobacterium, pigmented Prevotella, and Porphyromonas spp. and Bacteroides fragilis group. Management of these infections includes the administration of antimicrobials effective against the anaerobic as well as the aerobic pathogens.