We studied the ability of high-volume, low-pressure tracheal tube cuffs (Portex Soft Seal, Portex Profile, Mallinckrodt Lo-Contour and Mallinckrodt Hi-Lo tubes) to prevent leakage of fluid into the airway, in a model trachea and lung. Five tubes (7.0 and 8.0 mm internal diameter) of each type were used. Each tube was inserted into the model trachea and the cuff inflated until the intracuff pressure reached either 20, 30 or 40 cm H2O. The model lung was ventilated with a tidal volume of 700 ml and respiratory rate of 14 breath.min-1 at a compliance of 20 cm H2O. Ten millilitres of 0.01% methylene blue solution were infused over the cuff and the volume of fluid leaking past the cuff over 5 min was measured. The leak volume for the Soft Seal tube was less than that for the Profile or Lo-Contour tubes at all intracuff pressures (all p<0.05). Compared with the Hi-Lo tube, the volume leaking past the cuff for the Soft Seal tube was greater at an intracuff pressure of 20 cm H2O (p<0.05), whereas there was no significant difference between these two tubes at an intracuff pressure of 30 or 40 cm H2O. We conclude that the cuff of the Portex Soft Seal tube prevented leakage of fluid significantly more than that of the Portex Profile or Mallinckrodt Lo-Contour tubes, and to a similar degree to that of the Mallinckrodt Hi-Lo tube.