Abstract: A rotary disc valve is disclosed which generally includes a housing having an inlet side and an outlet side, and a disc rotatably mounted within the housing between the inlet side and the outlet side thereof. The disc includes an outlet bore which is generally aligned with the axis of rotation of the disc and extends from the outlet face of the disc partially through the disc. One or more inlet bores spaced radially outwardly from the axis of rotation of the disc extend from the inlet face of the disc partially through the disc and communicate with the outlet bore. The inlet bore or bores are located such that a bore may be selectively brought into communication with a single one of inlet side passages by rotating the disc until the bore is aligned with the desired passage. Since the outlet bore and an outlet passage are aligned along the center of rotation of the disc, the outlet bore stays in constant communication with the outlet passage in the outlet side of the housing as the disc is rotated.