An 80-year old woman with a history of tracheal stenosis, tracheostomy, and 3 months of increasing respiratory distress underwent tracheal dilatation under general anesthesia with jet ventilation. Tracheal dilatation was successfully performed via suspension laryngoscopy and jet ventilation. During emergence the patient developed decreased oxygen saturation, hypotension, and respiratory distress, requiring intubation and ventilatory support. During tracheostomy, anterior chest subcutaneous emphysema led to a diagnosis of tension pneumothorax. Chest tube placement facilitated tracheostomy and improved ventilatory and circulatory parameters. This article discusses the diagnosis and treatment of a tension pneumothorax under general anesthesia. Jet ventilation, spontaneous rupture of blebs or bullae, surgical trauma, or barotrauma are the 4 most likely explanations for a tension pneumothorax in this patient. Jet ventilation can cause pneumothorax, pneumomediastinum, or subcutaneous emphysema. Chronic obstructive pulmonary disease may cause blebs or bullae, which might rupture when exposed to positive pressure ventilation. Tissue trauma during dilatation or tracheostomy may cause a pneumothorax when positive pressure ventilation is employed. Barotrauma from high peak inspiratory pressure, rigid bronchoscopy, dilatation procedure, or jet ventilation may cause a pneumothorax. Prompt diagnosis and treatment will markedly decrease associated morbidity and mortality.