The literature data concerning respiratory function in cirrhosis of the liver are cited and reference is made to the results of a spirometric, gas analysis and 133-Xenon investigation of this parameter in 38 patients. Spirometry pointed to slight ventilatory incapacity of the restrictive type. Arterial gas analaysis showed respiratory alkalosis, usually accompanied by metabolic acidosis and slight hypoxyaemia. Examination with 133-Xe indicated that hypoxyaemia was not due to a shunt effect, since there was no excess of perfusion with respect to district ventilation. It was clear, on the other hand, that the pulmonary capillary reserve was almost exhausted. Such complete perfusion of the capillary bed may be due to increased cardiac output and, in part, to reduction of the respiratory surface caused by raising of the diaphragm and hypoventilation of the lung bases.