The invention provides a system (1000) for perfusing a lung ex vivo. The system allows for connecting the lung within a fluid perfusion circuit, flowing a perfusion fluid into the lung through a pulmonary artery interface (1022) and away from the lung through a pulmonary vein interface (1026), providing a respiratory gas to the lung for use in metabolism by the lung, the respiratory gas having a pre-determined composition of oxygen, and ventilating the lung through a tracheal interface (1024).
