Abstract: An apparatus for supplying a mixture of oxygen and an anesthetic gas at a predetermined flow rate and mixture ratio. The flow rate and mixture ratio are controlled by means of electrically operated throttle valves, responsive to output signals from an electronic control system, generated in accordance with data stored in the control system and with input signals applied to the computer from means for sensing the flow rates of the oxygen and anesthetic gas. Desired flow rate and mixture ratio data may be input by using a numeric keyboard, and are digitally displayed.