This experimental study was done to understand the functional difference and variables thought to be important in determing CO2 elimination and arterial oxygenation during HFJV and system J (System J means that an expiratory valve is attached to the expiratory port of the double lumen tube). In an experimental lung model, a plastic tube, simulating the traches, was intubated with a double-lumen tracheal tube. Ventilation was performed with a solenoid valve controlled high frequency ventilator. Changing the inspiratory time and driving pressure during HFJV and system J can linearly alter the tidal volume and airway pressure. There was a significant difference in airway pressure between the two modes of high frequency ventilation at I:E ratios of 1:2 adn 1:3. With air entrainment, HFJV provided more peak flow than system J and less FIO2 with and increasing driving pressures. Some functional charateristics of two high frequency ventilatory system using double-lumes tubes in a lung model are shown in this study.