OBJECTIVE: Massive perioperative blood product transfusion may be required with thoracic aortic operations and is associated with poor outcomes. We analyzed independent predictors of massive transfusion in thoracic aortic surgical patients undergoing deep hypothermic circulatory arrest. METHODS: The study consisted of 168 consecutive patients undergoing open thoracic aortic procedures involving deep hypothermic circulatory arrest between July 2005 and August 2008. We identified 26 preoperative and procedural variables as potentially related to blood product use, tested for association with total blood products transfused by multivariate linear regression model, and constructed logistic regression model for massive transfusion (requiring ≥ 5 units of transfused packed red blood cells between incision and 48 postoperative hours). RESULTS: Multivariate linear regression determined that 6 significant variables accounted for 42% of variation in total blood products transfused: age (P = .008), preoperative hemoglobin (P = .04), weight (P = .02), cardiopulmonary bypass time (P < .0001), emergency status (P < .0001), and resternotomy (P < .0001). Final predictive logistic regression model included 1-g/dL increase in preoperative hemoglobin (odds ratio, 0.54; 95% confidence interval, 0.43-0.69; P < .0001), 10-minute increase in cardiopulmonary bypass time (odds ratio, 1.15; 95% confidence interval, 1.05-1.26; P = .0026), and emergency status (odds ratio, 4.02; 95% confidence interval, 1.53-10.55; P = .0047. CONCLUSIONS: Cardiopulmonary bypass time, emergency status, and preoperative hemoglobin were independent predictors of massive transfusion. These variables, along with weight, age, and resternotomy, were associated with total blood product use in thoracic aortic operations involving deep hypothermic circulatory arrest.