OBJECTIVE The goal of this pilot study was to determine whether clinical criteria can identify blunt trauma patients with significant acute intrathoracic injury on chest radiograph. METHODS From January 2003 to May 2004, adult blunt trauma patients who received chest radiographs were prospectively enrolled at 2 urban trauma centers. Exclusion criteria were age less than 15 years, penetrating trauma, trauma more than 72 hours before presentation, isolated head trauma, and Glasgow Coma Scale score less than 14. Before chest radiograph viewing, providers recorded the following data: mechanism of injury, vital signs including oxygen saturation, patient symptoms, intoxication, distracting injuries, and the presence or finding of visible chest wall injury, chest palpation tenderness, pain on lateral chest compression, crepitus, and abnormal chest auscultation. Significant acute intrathoracic injury was defined as pneumothorax, hemothorax, aortic injury, 2 or more rib fractures, sternal fracture, or pulmonary contusion by blinded radiologist chest radiograph interpretation. RESULTS Of the 507 enrolled patients, 15 patients were excluded because chest radiograph was not performed. Significant acute intrathoracic injury was confirmed in 31 of 492 (6.3%) patients. Palpation tenderness and chest pain had the highest sensitivity (90%) as individual criteria for significant acute intrathoracic injury, and hypoxia had the highest specificity (97%). The combination of palpation tenderness and hypoxia identified all significant acute intrathoracic injury with the following screening performance with 95% confidence intervals (CIs): sensitivity 100% (95% CI 91% to 100%); specificity 50% (95% CI 45% to 54%); positive predictive value 12% (95% CI 9% to 17%); and negative predictive value 100% (95% CI 99% to 100%). CONCLUSIONS In this small sample, the combination of palpation tenderness and hypoxia identified all blunt trauma patients with significant acute intrathoracic injury while potentially eliminating the need for 46% of chest radiographs.