Bronchial thermoplasty has been found to be a safe and effective therapy for severe asthma. We report the case of a mediastinal hematoma and hemothorax developing in a 66-year-old woman several days after an uneventful bronchial thermoplasty of the right lower lobe. Evaluation revealed a bleeding right bronchial artery pseudoaneurysm. Pseudoaneuryms have been reported in association with other procedures involving the therapeutic application of thermal energy, and a single case of hemoptysis requiring bronchial artery embolization occurred in a clinical trial of bronchial thermoplasty. However, bronchial artery pseudoaneurysm with hemomediastinum and hemothorax has not previously been reported after bronchial thermoplasty.