Intrapleural instillation of fibrinolytic agents has been shown, in a number of studies, to be an effective and safe mode of treatment in complicated parapneumonic effusions and empyema, minimizing the need for surgical intervention. Streptokinase and urokinase are the fibrinolytics used, but the technique of instillation is not yet standardized. The usual dose of streptokinase is 250,000 IU, 100,000 IU for urokinase. Fibrinolytics are diluted in 30-100 mL normal saline and the success rate ranges 50-100%, depending on the stage of pleural effusion. Generally, fibrinolytics are more successful if used early in the process of pleural infection (in complicated parapneumonic effusions rather than in empyemas). Adverse reactions are rare, of the allergic type and more frequent for streptokinase. Urokinase is safer but more expensive.