Pneumothorax is the presence of air or gas in the pleural cavity. According to pathophysiology, there are several distinct entities, namely spontaneous (primary or secondary), traumatic or iatrogenic. Tension pneumothorax is an especially dangerous form, which can severely endanger the patient. Pneumothorax is diagnosed based on clinical presentation, chest x-ray or other imaging modalities. Computed tomography is the study of choice for the diagnosis of the underlying cause of secondary spontaneous pneumothorax. Pneumothorax is most commonly treated by tube thoracostomy: we place a chest tube (drain) into the pleural cavity through the fifth intercostal space and connect it to the drainage system. The drainage system uses the three-bottle principle, and the modern drainage systems incorporate the three receptacles in one portable casing. A tension pneumothorax can urgently be treated by thoracocentesis. Recurring pneumothoraces are treated either by pleurodesis or by surgical intervention. This article presents two patients from our department, treated for spontaneous pneumothorax. By describing these two patients, we will present clinical manifestations, differences in diagnostic approaches and treatment of primary and secondary spontaneous pneumothoraces.