Background: Viscoelastic hemostatic assays such as rotational thromboelastometry (ROTEM) are used to guide treatment of trauma induced coagulopathy. The authors hypothesized that ROTEM derangements reflect specific coagulation factor deficiencies after trauma. Methods: This was a secondary analysis of a prospective cohort study in six European trauma centers in patients presenting with full trauma team activation. Patients with dilutional coagulopathy and patients on anticoagulants were excluded. Blood was drawn on arrival for measurement of ROTEM, coagulation factor levels, and markers of fibrinolysis. ROTEM cutoff values to define hypocoagulability were as follows: EXTEM clotting time greater than 80 s, EXTEM clot amplitude at 5 min less than 40 mm, EXTEM lysis index at 30 min less than 85%, FIBTEM clot amplitude at 5 min less than 10 mm, and FIBTEM lysis index at 30 min less than 85%. Based on these values, patients were divided into seven deranged ROTEM profiles and compared to the reference group (ROTEM values within reference range). The primary endpoint was coagulation factors levels and fibrinolysis. Results: Of 1,828 patients, 732 (40%) had ROTEM derangements, most often consisting of a combined decrease in EXTEM and FIBTEM clot amplitude at 5 min, that was present in 217 (11.9%) patients. While an isolated EXTEM clotting time greater than 80 s had no impact on mortality, all other ROTEM derangements were associated with increased mortality. Also, coagulation factor levels in this group were similar to those of patients with a normal ROTEM. Of coagulation factors, a decrease was most apparent for fibrinogen (with a nadir of 0.78 g/l) and for factor V levels (with a nadir of 22.8%). In addition, increased fibrinolysis can be present when the lysis index at 30 min is normal but EXTEM and FIBTEM clot amplitude at 5 min is decreased. Conclusions: Coagulation factor levels and mortality in the group with an isolated clotting time prolongation are similar to those of patients with a normal ROTEM. Other ROTEM derangements are associated with mortality and reflect a depletion of fibrinogen and factor V. Increased fibrinolysis can be present when the lysis index after 30 min is normal.