DISCUSSION: Ipsilateral pneumothorax is a rare complication of EBUS-TBNA, whereas contralateral pneumothorax has not been reported before. Because pneumothorax without a biopsy is a rare complication, the possible causes have not been well described. Our patient developed contralateral pneumothorax due to positive pressure during ventilation causing rupture of emphysematous bulla. We speculate that this may have been due to a large EBUS scope wedging into a subsegmental lobar bronchi, which diverted the tidal volume during general anesthesia to the contralateral lung. Possible risk factors include a large tidal volume, dynamic inflation, and increased airflow obstruction. Since general anesthesia can obscure the presentation, it is important to communicate with the anesthesiologist about these serious complications, so that the tidal volume can be adjusted appropriately.