Pneumomediastinum is the presence of air in the mediastinum. It may occur as spontaneous, traumatic, or iatrogenic pneumomediastinum. Although spontaneous pneumomediastinum is usually observed in healthy young men, traumatic pneumomediastinum may be caused by blunt or penetrating trauma to the chest and neck. Pneumomediastinum is a clinical condition with potential complications that cause high morbidity and mortality rates. Pneumomediastinum also may develop without tracheal or oesophageal injury after spontaneous or blunt chest, neck and facial injuries, and it may be accompanied by pneumothorax. We treated two patients who had pneumomediastinum. Case 1 was a 20-year-old man who had pain and dyspnoea around the sternum for one hour, as a result of a blow from an elbow during a football match. Case 2 was a 23-year-old man who had a two-day history of dyspnoea and chest pain with no history of trauma. In both patients, diagnosis of pneumomediastinum was confirmed with thoracic computed tomography scans, and the condition resolved within five days of in-patient observation. In conclusion, the diagnosis of pneumomediastinum should be considered for all patients who present to the emergency department with chest pain and dyspnoea.