During the last three or four years, there has been a return to closed methods of drainage for empyema, with a rather more widespread adoption of these principles than on any of the previous occasions when this form of treatment had been adopted only to be discarded again partially. It is our belief that the causes of this widespread change or modification in treatment are the occurrence of streptococcus empyema in army camps, with a very high mortality attendant on rib resection, and the very prevalent misconception as to the action of the lungs in the presence of an open thorax. That there is some merit in draining pus from the chest, without leaving the pleural cavity open to the air, is apparent. From a study of the literature and an analysis of 172 of our own cases in which operation was done during what might be called this transitional period we have endeavored to ascertain what merits this form of treatment has, and to what class of cases among children it is applicable.Every few years a paper is written emphasizing the importance of not allowing air to enter the pleural cavity in draining it and advocating some particular device for accomplishing this end. Thus Robinson devised a very clever scheme of trephining a rib and applying suction apparatus. Von Eberts devised another technic of applying suction with a Politzer bag. Holt and Remsen described still other modifica¬ tions. All these methods were based on the same general principles.In more recent years, the same principles have been advocated again with changes in the devices used. Of the more recent methods may be mentioned those of Mazingo, Phillips and Whittemore. Some clinicians advocate irrigating with surgical solution of chlorinated soda.Some apply continuous suction, others intermittent suction, but all lay claim to success partly because they do not allow air to enter the pleural cavity and partly on account of their own particular apparatus. It is extraordinary that the belief-should be so widespread that an opening in the thorax necessarily causes collapse of the lung. It would seem that almost every surgeon who has ever operated for empyema must have observed, after evacuation of the pus, how the lung expands and contracts with respiratory efforts. At times the lung comes directly to the thoracotomy opening. It likewise seems strange that