Decortication of post-traumatic empyema (PTE) was performed in 27 patients from 1972 through 1977. All 27 patients had penetrating chest wounds and were refractory to antibiotics and tube thoracostomy. Factors associated with PTE included unrecognized diaphragmatic perforation, large hemothorax greater than 500 ml, pulmonary contusion, extrathoracic extension of hematoma within the chest wall, and incomplete expansion of the lung with initial tube thoracostomy. Prophylactic antibiotic usage did not prevent PTE nor lead to negative intrapleural cultures preoperatively. The timing of decortication varied with indication: two patients with infected pneumothorax had surgery within 1 week; 15 patients with infected pleural clot had surgery within 4 weeks; ten including nine who were readmitted to the hospital had surgery more than 4 weeks after injury. Prevention of PTE requires early recognition of hemo- or pneumothorax, early tube thoracostomy with complete evacuation of blood and expansion of lung, careful daily monitoring of subsequent fluid accumulation, and prompt evacuation when such fluid accumulates. Once PTE becomes well established and refractory to standard modalities, decortication with evacuation of the empyema cavity should be performed as soon as possible.