Thirty-seven septic patients with major multisystem trauma were evaluated by computed tomography (CT) to identify possible thoracic sources of infection. CT was 72% accurate in the diagnosis of empyema and 95% accurate in the diagnosis of lung abscess. While CT proved useful in demonstrating these sites of thoracic infections in septic trauma victims, the presence of concurrent thoracic pathology, particularly loculated hemothorax or hemopneumothorax and traumatic lung cysts with hemorrhage or surrounding parenchymal consolidation, introduced sources of diagnostic error. CT also proved helpful in guiding appropriate revisions of malpositioned and occluded thoracostomy tubes.