Purpose: The liver is the second most common organ injured by blunt abdominal trauma. The purpose of this study was to determine the utility of liver transaminase in screening blunt abdominal trauma patients for traumatic liver injury. Methods: We retrospectively reviewed the medical records of 231 patients who sustained blunt trauma and were at risk for traumatic liver injury between June 2009 and August 2010. All of them underwent a focused assessment with sonography for trauma (FAST) and abdominal computed tomography (CT). Based on the diagnosis of abdominal CT, patients were divided into two groups: group I with liver injury and group II without liver injury. We compared the two groups and calculated the sensitivity, the specificity and the predictive values of serum aspartate aminotransferase (AST) and serum alanine aminotransferase (ALT) by using multiple cutoff values. Results: Of 231 patients with no abdominal free fluid in the FAST, 33 had traumatic liver injury on abdominal CT. The mean AST and ALT levels in group I (311.6 IU/L and 228.1 IU/L, respectively) were significantly higher than the values in group II (48.4 IU/L and 35.6 IU/L, respectively). The cutoff to distinguish liver injury is 60 IU/L for AST and 58 IU/L for ALT, with 93.8% sensitivity and 79.8% specificity for AST, and 90.6% sensitivity and 87.4% specificity for ALT. Conclusion: We recommend that all patient with suspected blunt abdominal trauma be evaluated using serum liver transaminase as a screening test for liver injury even though no abdominal free fluid is shown on the FAST. If AST > 60 IU/L and/or ALT > 58 IU/L, abdominal CT was useful to confirm liver injury in this study.