Acute multiloculated thoracic empyemas incompletely drained by tube thoracostomy alone usually require operation. To avoid a thoracotomy yet treat this difficult problem, intrapleural fibrinolytic agents were employed. Between April 1, 1990, and April 1, 1993, 13 consecutive patients presenting with a fibrinopurulent empyema were demonstrated to have incomplete drainage. To facilitate drainage, streptokinase, 250,000 units in 100 mL 0.9% saline solution (3 patients), or urokinase, 100,000 units in 100 mL 0.9% saline solution (10 patients), was instilled daily into the chest tube, and the tube was clamped for 6 to 12 hours followed by suction. This routine was continued daily for a mean of 6.8 +/- 3.7 days (range, 1 to 14 days) until resolution of the pleural fluid collection was demonstrated by computed chest tomography and clinical indications. This regimen was completely successful in 10 of 13 patients (77%), who had resolution of the empyema, eventual withdrawal of chest tubes, and no recurrence. Two patients, both pediatric liver transplant patients, had an initial good response but eventually required decortication. One patient with a good radiographic response became increasingly febrile during streptokinase therapy and underwent a thoracotomy, but no significant undrained fluid was found. This patient's continued fever was believed to be a streptokinase reaction. Urokinase was used subsequently. No treatment-related mortalities or complications occurred. Intrapleural fibrinolytic agents, especially urokinase, are safe, cost-effective means of facilitating complete chest tube drainage, thereby avoiding the morbidity of a major thoracotomy for 77% of a group of multiloculated empyema patients who traditionally would have required open surgical therapy.