The tracheas of 20 ASA grade 1 and 2 patients were each consecutively intubated with an oral and nasal cuffed tracheal tube. Measurements of tube movement, as the position of the head and neck altered, were made with a fibreoptic bronchoscope. Both oral and nasal tubes moved an average distance of 15 mm towards the carina with head and neck flexion and 8.5 mm away with head and neck extension. Movement in both directions occurred with lateral rotation of the head. Optimal placement of tracheal tubes can be aided with a single guide mark placed 3 cm proximal to the cuff and 8 cm proximal to the distal end, which may reduce complications arising from this movement. This is a better method in women than inserting a pre-determined length of tracheal tube measured from the lips or nares. However, current guide marks vary in their position relative to the cuff and tip of the tube.