The reinfusion of extravasated blood is rapidly becoming an accepted procedure. A careful search of the literature to date has revealed only one reported case of autotransfusion of blood from the pleural cavity. Therefore we believe that the three reports given here of the use of autotransfusion in cases of hemothorax are sufficiently interesting for presentation. Autotransfusion, i. e., the reinfusion of the patient's own blood, has obtained increasing attention during the past few years following the reports in 1914 of Johannes Thies1of Leipzig, who reinjected blood obtained from the abdominal cavity in cases of ruptured tubal pregnancy. However, according to Kubányi2of Hungary, the idea appears to have originated in England, as William Highmore3in 1874 suggested its use, and in 1885 there is a report of its actual application by A. G. Miller,4who collected and reinjected with gratifying results blood lost during