Hypothesis: Survival following massive transfusion in patients who have undergone trauma has improved during the past 10 years. Design: Retrospective cohort study. Setting: Academic level I trauma center in an urban community. Patients: All patients who underwent trauma and who received greater than 50 U of packed red blood cells or whole blood in the 48 hours following admission to the emergency department. Interventions: Data were obtained from blood bank records, the trauma registry, patient medical records, and hospital purchasing records. Patients were divided into 2 groups for comparison (early [1988-1992] and late [1993-1997] periods). Main Outcome Measures: Survival and changes in trauma care provision. Results: Survival following massive transfusion in patients who have undergone trauma has significantly increased during the past 10 years (16% vs 45%, early vs late period, P=.03). Factors associated with poor outcome included male sex, major vascular injury, high Injury Severity Score, severe acidosis, prolonged hypotension, refractory hypothermia, and decreased use of platelet transfusion (all P<.05). In the later period, there was more aggressive correction of coagulopathy, more efficient use of warming measures, decreased operative times for the initial operation, and increased use of component therapy tall P<.05). Conclusions: Survival following massive transfusion has significantly (P=.03) increased during the past 10 years. Factors that may have contributed to this include more effective and efficient rewarming procedures, improved application of damage control techniques, more aggressive correction of coagulopathy, and improved blood banking procedures.