A 68-yr-old man presented for pharyngeal biopsy under general anaesthesia. Coincidentally he was found to have a large mediastinal mass. The evaluation of this patient is described. The exact risk of catastrophic airway collapse on induction of anaesthesia in patients with mediastinal masses is controversial but probably small. As there is no test to prevent airway collapse, it is suggested that attempts at biopsy be performed with regional anaesthesia after radiotherapy.