Emphysema in the retropharyngeal space and mediastinum is usually caused by one of the three pathological conditions: 1. Infections due to gas-forming microorganisms such as mediastinitis. 2. Traumatic dusruption of cutaneous and mucosal barriers. 3. Spontaneous rupture of the pulmonary alveoli. This case report illustrates the direct propagation of air from a mucosal bucco-gingival tear through the submandibular, cervical, retropharyngeal and posterior mediastinal space caused by a sudden rise in the pressure of the air in the bucco-pharyngeal cavity.