Changes in the tracheal tube tip to carina distance were measured by radiographic screening following various head postures in 45 children undergoing cardiac catheterisation under general anaesthesia who were intubated via nasal and oral routes. Extension of the head moved the tracheal tube away from the carina and flexion moved it towards the carina in both routes. Endobronchial intubation was noted during neck flexion in a significant proportion of children intubated orally but none occurred during nasal intubation. Extension produced greater upward movement of the tracheal tube tip in the oral route than the nasal route. In contrast, flexion produced greater downward movement in the nasal route in some patients. The direction of movement with lateral rotation and use of a shoulder roll was inconsistent.