CT revealed the presence of epidural emphysema as an incidental finding in a 13-year-old boy in whom mild infrequent coughing during an asthmatic attack resulted in a pneumomediastinum and subcutaneous emphysema. Epidural emphysema was not associated with neurological symptoms. The CT images demonstrated the pathway of air leakage from the posterior mediastinum through the intervertebral foramina into the epidural space. Repeat CT showed spontaneous resolution of the epidural emphysema.