INTRODUCTION: The presence of fluid collection in the pleural cavity is a frequent clinical problem that requires drainage for diagnostic and therapeutic purposes. Aim of our study is the retrospective evaluation of our experience in diagnostic and therapeutic thoracic drainage, to stress the cause of failure and to emphasise the cost-effectiveness of the technique. MATERIALS AND METHODS: From January 1995 to May 2009, 564 therapeutic and diagnostic ultrasound (US) guided percutaneous drainages of pleural fluid collection were performed in 412 patients. RESULTS: The macroscopic, biochemical, cytological and microbiological examination of the drained fluid diagnosed the presence of 80 (19.4%) transudates, 101 (24.5%) non neoplastic exudates, 55 (13.4%) neoplastic exudates, 152 (36.9%) empyema and 24 (5.8%) haemothorax. There were no major complications. Minor complications were present in 23/564 cases (4.0 %). CONCLUSIONS: The US guided puncture of the pleural fluid collection allows a high rate of success (in correct detection and drainage of chronic pleural effusions), reduces the rate of complications and is well accepted by patients.