A refined bronchoscopic method of sampling bronchial secretions is presented. The results show that this gives higher yields of aerobic pathogens than examination of expectorated sputum and the method also avoids pharyngeal contamination in suspected cases of anaerobic lung infection. Our results indicate that anaerobic organisms do not play a major role in causing sputum purulence in patients with chronic bronchitis, bronchogenic carcinoma or with less florid degrees of bronchiectasis. Anaerobic infections did not appear to occur as often as suggested by some reports from the United States.