BACKGROUND AND OBJECTIVES: Traumatic haemorrhage often requires initiation of a massive haemorrhage protocol (MHP). The primary aim of this exploratory Emergency Department (ED) study was to examine the utility of point of care Viscoelastic Haemostatic Assays (VHA) in terms of accuracy. The primary outcome was prediction of the need for massive transfusion (MT) at 24-hours. METHODS: Prospective observational study of consecutive trauma patients investigated with reported using STARD guidelines. Patients in an Australian ED setting < 1-hour from triage enrolled in a three-year window. The point-of-care device used was a TEG6s™ (Haemonetics, Braintree, MA, USA). The primary outcome was accuracy VHA testing for predicting MT delivery at 24-hours (an internationally recognised of massive transfusion was used). Other trauma outcomes such as product transfusion, injury severity score (ISS) and demographics were recorded. For analysis of accuracy the cohort was divided into VHA-normal (n = 44) and VHA-abnormal (n = 70) binary groups. Secondary outcomes included utility of TEG6s™ individual components and accuracy of VHA when combined with validated MHP decision scores. RESULTS: Among eligible cases (n = 114) in-patient mortality was 7.0% with 91.2% receiving transfusion. Presence of (any) abnormal VHA result provided a 73.6% (95%CI 59.7-84.7) sensitivity and 49.3% (95%CI 36.1-62.3) specificity for predicting MT. Citrated Functional Fibrinogen (CFF) component had a higher performance for MT "rule-in" specificity (86.9%). When VHA was combined with validated MHP decision scores performance was increased. For example, normal VHA with Trauma Associated Severe Haemorrhage score < 8.5 was observed to yield a sensitivity of 96.2% for MT requirement rule-out. Further studies should examine if VHA test parameters can be added or (replace INR) in the existing clinical scores used to make decisions about transfusion in ED patients. CONCLUSION: The standalone performance of early VHA testing in the ED setting was insufficient to reliably for predict a need for massive transfusion.