Resuscitative endovascular balloon occlusion of the aorta is a new procedure for adjunctive management of critically injured patients with noncompressible torso or pelvic hemorrhage who are in refractory hemorrhagic shock, ie, bleeding to death. The anesthesiologist plays a critical role in management of these patients, from initial evaluation in the trauma bay to definitive care in the operating room and the critical care unit. A comprehensive understanding of the effects of resuscitative endovascular balloon occlusion of the aorta is essential to making it an effective component of hemostatic resuscitation.