Bleeding is clearly a major cause of morbidity and death after trauma. When bleeding is attributable to transection of major vessels, surgical repair is appropriate. Posttraumatic microvascular bleeding attributable to coagulopathy secondary to metabolic derangements, hypothermia, and depletion or dysfunction of cellular and protein components requires a different approach. Although transfusion of blood products may be necessary to replace the blood loss, it does not always correct the problem of microvascular bleeding. The type of injury, mode of care, and treatment objectives differ significantly for combat-wounded soldiers versus civilian trauma patients. Although hemorrhage is responsible for 50% of combat deaths, published information about coagulation monitoring among combat patients is very limited. These articles summarize the appropriate monitoring of hemostasis among combat trauma patients, review the unique nature of combat casualties and the medical system used to treat them, and discuss information available from civilian studies. Because the development of coagulopathy is relatively infrequent in the young, otherwise healthy, military population, the routine screening measures currently used are adequate to guide initial blood product administration. However, as new intravenous hemostatic agents are used for these patients, better laboratory measures will be required. Although hemorrhage is the leading cause of death for combat casualties, catastrophic hemorrhage is rarely a prehospital combat medical management problem because, when it occurs, it tends to cause death before medical care can be provided. In civilian environments, most seriously injured victims can be reached and transported by emergency medical services personnel within minutes; in combat, it often takes hours simply to transport casualties off the battlefield. In combat situations, even if the transport distances are small, the hazardous nature of the forward combat areas frequently prevents medical personnel from quickly reaching the wounded. Furthermore, whereas civilian blunt trauma victims may have a "golden hour," casualties with penetrating battlefield trauma often have only a "platinum 5 minutes." Because of the challenges of treating hemorrhage during combat, it is important for military medical personnel to understand their options for treating hemorrhage quickly and efficiently. These articles discuss the causes of posttraumatic microvascular bleeding and the potential treatment options for controlling catastrophic hemorrhage in combat areas.