One hundred eighty-seven diagnostic and therapeutic interventional procedures in the pleural space were performed by using sonographic guidance. These consisted of diagnostic aspiration (118), drainage of malignant and nonmalignant effusions (41), empyema drainage (17), pleural sclerotherapy with tetracycline or bleomycin (7), and pleural biopsy (4). Diagnostic aspiration was performed with 20-gauge needles, and therapeutic and empyema drainages were performed by trocar technique with either a 7-French Sacks catheter or a specially designed empyema drainage catheter. Pneumothoraces were seen in 3% of the patients, and most of these were treated by the radiologist with placement of a Heimlich valve. We conclude that the use of sonography allows rapid localization of pleural fluid collections and instant monitoring of drainage of noninfected fluid collections and empyemas.