Purulent bronchitis of varying extent developed in approximately 35 per cent of the cases and often prolonged the course of the illness to a considerable extent. Bacteriologic studies showed that it was invariably associated with a mixed infection of the bronchi with B. influenzæ and other bacteria, in most instances the pneumococcus, and indicated that it should be regarded as a complication rather than as an essential part of influenza. Its clinical features consisted of a mild febrile reaction, frequent cough with the raising of considerable amounts of purulent sputum, and the physical signs of a more or less diffuse bronchitis. It led to a varying degree of bronchiectasis in at least some instances. Pneumonia complicating influenza presented a very diversified picture and appeared to have only one constant character, namely, that influenza was the predisposing cause. It may be best classified on an etiologic basis since the clinical features to some extent and the pathology to a much greater extent depended upon the infecting bacteria in a given case. Bacteriologic examination showed that a very large proportion of the cases was due to infection with the different immunologic types of pneumococci or to a mixed infection with B. influenzæ and pneumococci. The types of pneumococci commonly found in normal mouths, namely, II atypical, III, and IV, comprised approximately 88 per cent of these, the highly parasitic Pneumococci Types I and II, but 12 per cent. A small number of cases were due to hemolytic streptococci or to mixed infection with B. influenzæ and S. hemolyticus. No certain evidence was obtained that pneumonia was due to B. influenzæ alone. This organism was present in varying numbers, however, in approximately 80 per cent of the sputums examined, and it seems fairly certain that it must have played at least a part in the development of the pneumonia in many of the cases in which it was found. Superimposed infections with other types of pneumococci than those primarily responsible for the development of pneumonia, with hemolytic streptococci and with Staphylococcus aureus occurred frequently in cases of pneumococcus or mixed pneumococcus and B. influenzæ pneumonia and undoubtedly contributed to a considerable extent in increasing the number of deaths.