Pneumothorax was recognized as a potential hazard of mechanical ventilation after tracheal intubation. Excessive pressure the trachea during general anesthesia could produce lung rupture and pneumothorax. The incidence of pneumothorax has increased as a result of increased application of invasive diagnostic and therapeutic procedures. Emphysematous bleb rupture afterlaryngospasm, bronchospasm, or cough may be causes of pneumothorax. Tension pneumothorax during anesthesia is often difficult to diagnosis, but it needs prompt dignose and treatment. We experienced 3 cases of tension pneumothorax during and after general anesthesia.