Strict anaerobic microrganisms (Fusobacterium, Veillonella, Bacteroides melaninogenicus, Peptostreptococcus, Actinomyces or anaerobic "diphtheroids') were isolated from expectorated sputum of hospitalized patients with chronic bronchitis. It is noteworthy that the anaerobic microorganisms were isolated from. 10-³ dilution of fluidified sputum and were not recovered from pharyngeal cultures in 83% of the isolates. These results indicate the bronchial origin of the strict anaerobic microorganisms and can not borne out the conclusion that sputum was contaminated with the anaerobic bacteria in pharynx and oral cavity.