Pulmonary infection is a fairly common postoperative complication, and the accompanying pathologic changes vary according to the avenue of infection, the amount, distribution and virulence of the infective organism, the relative resistance of the patient, the length of time the infection has been present, and the treatment. If abscesses result, they vary greatly in size and location. They may be simple, multiple or multilocular. They are usually surrounded by a peripheral zone of pneumonia, which may be circumscribed or extensive, and in various stages of resolution or liquefaction. In the more chronic stages, purulent bronchitis or bronchiectasis usually develops. Long continued infection results in thickening of the walls of the abscess, of the adjacent pleura, and fibrosis of the lung. For such a variety of pathologic lesions there can be no single descriptive term, but "chronic pulmonary suppuration" seems the most comprehensive and adequate. In a series of 692 cases