In many institutions, the standard treatment of symptomatic and large pneumothoraxes has been with surgically placed large-bore (22-32-F) chest tubes. During the past 3-4 years, the authors used small catheters (7, 8.2, and 9.4 F) to decompress 30 pneumothoraxes (15 under tension) resulting from percutaneous lung biopsy. The catheters were inserted under computed tomographic or fluoroscopic guidance for the treatment of large (greater than 35%) or symptomatic pneumothoraxes. Twenty-eight of 30 patients were treated successfully with the small catheters alone; two patients underwent surgical placement of 32-F tubes (4 and 12 hours later) because of incomplete resolution of the pneumothoraxes. This series demonstrates that small-caliber catheters effectively decompress pneumothoraxes and that they can be inserted expeditiously by radiologists in the radiology department.