The severely injured trauma patient often arrives in the emergency department bleeding, coagulopathic and in need of a blood transfusion. The diagnosis and management of these patients has vastly improved with a better understanding of acute traumatic coagulopathy (ATC). In the emergency setting, traditional laboratory coagulation screens are of limited use in the diagnosis and management of life-threatening bleeding. Whole blood assays, such as thrombelastography (TEG) and rotational thrombelastometry (ROTEM) provide a rapid evaluation of clot formation, strength and lysis. Rapid diagnosis of ATC and aggressive haemostatic transfusion strategies utilizing early high doses of plasma are associated with improved outcomes in trauma. At present there is no accurate guide for transfusion in trauma, therefore blood and clotting products are administered on an empiric basis. Targeted transfusion therapy for major trauma haemorrhage based on comprehensive and rapid measures of coagulation e.g. TEG/ROTEM may lead to improved outcomes while optimizing blood utilization. Evidence for the clinical application of TEG and ROTEM in trauma is emerging with a number of studies evaluating their ability to diagnose coagulopathy early and facilitate goal-directed transfusion. This review explores current controversies and best practice in the diagnosis and management of major haemorrhage in trauma.