Abstract: A fluid control valve for use with apparatus for medical use. Commercially available valves which operate by electrical, hydraulic or pneumatic means are often expensive and bulky. They may require excessive power to operate them and can be noisy during operation due to moving parts and fluid flow through internal pathways. The valve of the present invention has a valve seal (1) mounted between inlet (A) and outlet ports (B), with the seal including a valve closure member (4) operated by means of a control fluid fed through a control port (C) in the valve body. In operation a pressure differential acting to open and close the valve is set up between the inlet and outlet ports and the control port to operate the valve. This design results in cost savings and performance benefits compared with the prior art.