The purpose of this study was to identify the utility of thoracic computed tomography (TCT) in blunt trauma patients with a normal admission chest radiograph (CXR). A retrospective study was performed of 200 consecutive blunt trauma patients who received both CXR and TCT. One hundred and forty-three patients had a normal screening CXR; 36 of these patients (25%) had an abnormal TCT. TCT changed the management in only nine of these patients (6%): two required serial CXR for occult pneumothorax, four received additional imaging of the spine, and three were admitted to a monitored bed. Fifty-seven patients had an abnormal initial CXR. Of these, 41 (81%) had an abnormal TCT. TCT changed management in 21 (37%) of these patients: two aortic injuries identified, 12 aortic injuries excluded, two chest tubes placed, one patient taken to the Operating Room, and four patients required further diagnostic evaluation. TCT was significantly more likely to alter management in patients with an abnormal admission CXR (6% vs 37%, P < 0.001). TCT is of limited utility in patients with a normal admission CXR. A diagnostic strategy of obtaining TCT only in patients with abnormal CXR or high-risk mechanism of injury can result in significant cost savings without adversely affecting patient outcomes.