A pneumothorax occurs when the visceral or parietal pleura is breached and air enters the pleural space. This leads to loss of the negative intrapleural pressure and lung collapse. Pneumothoraces may be classified into ‘simple’, ‘tension’ or ‘open’ according to the underlying pathophysiology. A chest radiograph is essential in the diagnosis and management of pneumothoraces. Tension pneumothorax is a medical emergency, relieved initially with needle thoracentesis, but treated definitively with a chest drain. The latter is inserted in all cases where aspiration is unsuccessful in controlling symptoms in a simple pneumothorax. Specialist opinion should be sought if there is persistent air leak from the drain or the lung fails to re-expand after four days. A chest drain is used to drain air, fluid or pus from the pleural space. Proper attention should be paid to patient preparation, which should include full asepsis and appropriate positioning of the patient before insertion. A chest drain is usually inserted under local anaesthesia in the ‘safe triangle’ in the lateral chest wall using blunt dissection. The drains should not be clamped in cases of pneumothorax, and the drainage bottle should always be kept below the level of the patient's chest.