The occurrence and varying incidence of the staphylococcus in infections of the lung and of the pleura have been commented on by a number of observers, but the significance of pulmonopleural lesions due to the staphylococcus appears to have been overlooked. The literature consists essentially of statistical presentation of the incidence of the staphylococcus in pleuropulmonary infections, although staphylococcic pneumonia has been the subject of some separate discussion. Despite the fact that higher mortality has been noted, staphylococcic pleural infections have been included with the other bacteriologic varieties as if their pathogenesis, symptoms and treatment presented no appreciable differences. We believe that there are distinctive features in the pathogenesis and pathologic changes and in the treatment of staphylococcic pulmonopleural suppuration. The lesion in the form of empyema or pyopneumothorax will be described as an entity, and we shall attempt to show that its consideration as such leads to more