SummaryUnrecognised accidental oesophageal intubation remains an important cause of morbidity and mortality in anaesthetic practice. We have evaluated a new method of distinguishing tracheal from oesophageal intubation using a simple adaptation of an ordinary stethoscope which is inserted into the patient end of the breathing system. We call this technique 'airway auscultation'. Characteristic sounds are heard with the stethoscope during inflation and deflation which allow the observer to diagnose the position of the tube. When the tube is in the trachea loud breath sounds are heard. In contrast, when the tube is in the oesophagus either squeaks or a flatus-like noise is heard or else there is no sound. In 100 healthy adults two observers rapidly identified 99 intubations correctly in a randomised single-blind trial. We recommend further widespread evaluation of this device as it appears to be an effective, simple and rapid method of detecting oesophageal intubation and confirming tracheal intubation which may be of particular use in situations where capnography is not available.