Over a 5-year period, 65 adult patients with empyema thoracis were treated. The cause of the empyema was postpneumonic in 52%, postresectional in 24%, a complication of minor surgical procedures in 14%, posttraumatic in 5%, and the result of miscellaneous causes in 5%. In the postpneumonic group, infection resulted from a single aerobic organism in 41%, multiple aerobic organisms in 9%, single anaerobic organisms in 12%, and mixed aerobic-anaerobic organisms in 18%. Peptostreptococcus, Streptococcus viridans, Staphylococcus epidermidis, Peptococcus, Staphylococcus aureus, and diphtheroids were the most common organisms, accounting for 55% of bacterial isolates. All 34 patients with postpneumonic empyema were initially treated with drainage, which was successful in two thirds. The remainder, 12 patients, ultimately required thoracotomy. Decortication was combined with intrathoracic transposition of extrathoracic skeletal muscles in 9 patients. There was no reoperation or recurrence of infection, and thoracoplasty was avoided; residual spaces were filled by the transposed muscle.