Pneumothorax is an abnormal collection of air or gas in the pleural space that separates the lung from the chest wall and may interfere with normal breathing. It is classified on the basis of its initial presentation (ie: spontaneous and traumatic). In this book, the authors present current research and an overview in the study of the classification, treatment and prognostic factors of pneumothorax. Topics include the treatment of primary spontaneous pneumothorax; the pathology of pneumothorax and multiple pulmonary cysts associated with Birt-Hogg-Dube syndrome; and management of pneumothorax in the single lung.