The need for decortication to cure primary bacterial (nontuberculous) empyema was evaluated in 112 consecutive patients. Twenty-eight patients (25%) were cured by thoracentesis alone. Intercostal chest tube drainage was required in 43 (39%) and decortication in 41 (36%). Although hospital stay was shortened by 5 days for those who had decortication, the difference was statistically insignificant. Penicillin failed to eradicate infection in nine of 17 patients, four of whom had Bacteroides organisms. There were no therapeutic failures among 46 patients treated with clindamycin and gentamicin. We conclude that conservative therapy, such as thoracentesis, antibiotics directed against anaerobic bacteria, and intercostal tube drainage (thoracostomy), was adequate to achieve clinical and physiologic resolution in about two thirds of all patients with primary bacterial empyema. The remaining one third required decortication. Rib resection and Eloesser flap procedures seem to be unnecessary in the treatment of primary bacterial empyema.