Pulmonary contusion, implying interstitial and alveolar injury without significant laceration, has been accepted as the primary lung injury in nonpenetrating chest trauma. Computed tomographic (CT) findings were compared with those of chest radiography in 85 consecutive patients with chest trauma in which there was a pulmonary radiodensity consistent with pulmonary contusion or patients with a history of severe chest trauma with normal parenchyma despite rib fractures, hemothorax, pneumothorax, or widened mediastinum. CT was found to be more sensitive than radiography in that 151 abnormalities (excluding rib fractures) were demonstrated on radiographs versus 423 abnormalities on CT scans, and 99 lacerations were seen on CT scans versus five on radiographs. Pulmonary lacerations were classified into four types on the basis of CT findings and mechanism of injury: compression rupture, compression shear, rib penetration, and adhesion tears. In these cases, pulmonary laceration was shown to be an integral component of the mechanism of injury in pulmonary contusion, pulmonary hematoma, pulmonary cyst or pneumatocele, or cavitation in pulmonary contusion.