Background: Thyroidectomy and parathyroidectomy have become safe procedures with low postoperative morbidity and complication rates—hypocalcemia, RLN injury and postoperative hematoma being the most common. In our institution the risk of hematoma following sutureless technique is 1%.¹ Pneumothorax following thyroidectomy and parathyroidectomy has only been reported a few times in the literature without a clear etiology. Materials and methods: Retrospective review of the complication database of the Royal North Shore Endocrine Surgical Unit from 2000 to 2018. Results: Three cases of pneumothorax or pneumomediastinum were found following thyroidectomy or parathyroidectomy with an incidence of 0.02%. A recent case of pneumomediastinum and subcutaneous emphysema following an open parathyroidectomy was attributed to the Valsalva maneuver at the end of the case. Two further cases of pneumothorax at our institution occurred post parathyroidectomy. In both cases, a laryngeal mask was used and Valsalva maneuver (VM) was not performed. All cases were managed conservatively and made a full recovery. Conclusion: The combination of pneumomediastinum with subcutaneous emphysema in the most recent case is likely from a ruptured bulla secondary to Valsalva maneuver or lung injury during mediastinal dissection. This likely caused an air leak with gas tracking up into the neck from the mediastinum. The probable etiology in the other two cases is a negative mediastinal pressure created from laryngospasm with an open neck wound and dissection in the inferior neck and superior mediastinum.