This chapter describes resuscitative endovascular balloon occlusion of the aorta (REBOA). This is a strategy for addressing severe torso hemorrhage from trauma (and increasingly other non-trauma causes) using a temporary aortic occlusion balloon advanced from the femoral artery into the aorta. The objective of REBOA is to slow severe hemorrhage, to buy time for blood product resuscitation, and to facilitate definitive hemostasis. This technique includes both complete and partial occlusion of either the thoracic or the abdominal aorta. The history of REBOA, patient indications and contraindications, insertion technique, patient management during occlusion, and catheter removal are all described in detail. Potential complications are also discussed.