Computerized tomography(CT) is an effective technique in the initial evaluation of the abdomen and head following blunt trauma. To evaluate the efficacy of CT of the thorax, a retrospective study comparing early thoracic CT scanning with initial chest roentgenogram (CXR) was carried out on 134 patients with blunt trauma on the chest. Among 134 patients, 45 patients had normal initial chest roentgenogram and 24 patients showed normal CT findings. Sensitivities of diagnosing pneumothorax and pleural effusion by CXR were low (46.2 and 62.9% respectively), whereas 71.4%(45/63) of patients had thoracostomy only by CXR. Although sometimes abused, CT of the thorax is effective in the initial diagnosis.