Cuffed tracheal tubes are becoming increasingly popular in paediatric anaesthesia and intensive care medicine. To avoid cuff related complications and airway morbidity, a thorough understanding of cuff volume/pressure behaviour and management is required. In this study, the outer cuff diameter and form stability of the cuff at high cuff pressure were assessed in a series of different paediatric cuffed tracheal tubes with internal diameter of between 3.0 and 5.0 mm. The main findings were that small amounts of inflated air led to a rapid increase in cuff pressure and volume and that the outer cuff diameters increased to 2-2.5 times the age-corresponding internal tracheal diameter following inadvertent syringe inflation. Careful cuff inflation under cuff pressure monitoring and/or automatic cuff pressure release is recommended in paediatric tracheal tube cuffs to prevent airway damage caused by manual inflation, pilot balloon compression and nitrous oxide diffusion.