The medical records of 61 children 0 to 18 years of age treated for empyema complicating pneumonia from 1977 to 1989 were reviewed with attention to clinical presentation, bacteriology, treatment and outcome. Streptococcus pneumoniae was the most common infecting organism, followed by Staphylococcus aureus, other streptococcal species, anaerobes, Haemophilus influenzae type b, Pseudomonas aeruginosa, and Eikenella corrodens. No organisms were recovered in 39% of patients. Twelve patients were treated successfully with antibiotics and thoracentesis alone, 23 patients underwent close tube thoracostomy and 26 required decortication. A thickened pleural "peel," scoliosis and opacification of a hemithorax on chest radiograph, as well as low pleural pH and glucose concentration, were associated with a poor response to medical management. A scoring system was developed to define the severity of pleural disease. In patients with severe pleural infections, decortication allowed more rapid defervescence (2.2 vs. 6.5 days) and earlier hospital discharge (4.4 vs. 12.4 days) than did closed tube thoracostomy (P less than 0.001).