background: Computed tomography (CT) is an important diagnostic modality in the evaluation of blunt head and abdominal injuries, but it has not been routinely used to evaluate blunt chest trauma. methods: One hundred seventy stable patients with blunt thoracic trauma were evaluated with chest x-ray (CXR), and subsequently by CT. results: Of a total of 131 fractures, 53% were identified on initial CXR, 39% on CT, and 26% were not seen on either study. Twenty-one pneumothoraces were seen on CT but not on CXR. Chest tubes were placed in 8 patients and 12 patients were observed without incident. One hemothorax identified by CT scan alone required treatment. Four of 6 diaphragmatic injuries were seen on CT and 2 on CXR. Parenchymal abnormalities were apparent in 189 lung fields on CT and in 66 lung fields on CXR. Most represented atelectasis and did not require treatment. Altogether, CT scanning resulted in changes in management for 11 patients (6%). conclusions: Although CXR is less sensitive in detecting parenchymal and pleural injuries than CT, the majority of the injuries identified by CT alone are minor and require no treatment. CXR remains the primary modality for diagnostic evaluation of blunt thoracic trauma.