Background and purpose.In percutaneous placement of central venous catheters an inadvertent, direct lesion of the lung parenchyma can occur. This is a cause of iatrogenic pneumothorax, whose incidence is approximately 1 to 4%, largely dependent on the experience of the operator, the site of venipuncture and proba-bly the technique employed. Initial treatment currently ranges from observation alone to formal tube-thoracostomy. In an attempt to define the best initial treatment, if any, we reviewed our personal series and contributions from the literature. As a result we have produced a flow-chart proposing a rational treatment of this frequent complication. Patients and Methods.One thousand four hundred twenty-one ports were placed in patients at the Department of Surgery of the European Institute of Oncology in Milan through an infraclavicular standardized percutaneous subclavian approach. They were placed during the 60-month period from January 1, 1996 to December 31, 2000 for long-term chemotherapy treatment of solid tumours. Chest upright X-rays were obtained post-operatively in all cases to check the correct position of the catheter tip and the presence of pneumothorax. Results.Twenty-two patients out of 1421 (1.54%) experienced a radiologically-proven pneumothorax, ranging from 5 to 70% of the affected pleural space. Sixteen patients out of 22 (72.7%) with minor portions of affected pleural space received simple observation. In these patients the most common finding was an uncomplicated tachycardia (more than 100 beats/min); 8 of them did not complain of any symptoms. Six patients (27.2%) un-derwent an additional procedure (3 tube-thoracostomies and 3 aspirations of the pleural space), claiming symptoms of chest pain and various degrees of dyspnea. Tube thoracostomy was mainly adopted at the beginning of our experience, and in patients with a severe degree of pleural involvement (55 to 70% of the pleural space). Aspiration, instead, was used more recently and in patients with varying degrees of pleural space involved, ranging from 40 to 60%. Conclusions.Looking at our own series and literature data, patients with iatrogenic pneumothorax following central venous cannulation who do not have a severe underlying pulmonary disease can be reassured, at the time of diagnosis, that surgery is usually unnecessary and tube thoracostomy is rarely needed. Simple aspiration of the pleural air by means of a central venous catheter inserted percutaneously into the pleural space under local anesthesia should be considered, even if the amount of affected pleural space is more than 50%, before opting for a formal tube-thoracostomy using small-bore tubes.