Abstract: A mixing valve assembly comprises a body portion having a cylindrical bore extending therethrough and a pair of entrance channels for the admission of two dissimilar fluids (e.g. hot water and cold water), each such channel communicating with the bore through an opening in the wall of the bore. A mixing control member having a cylindrical plug is mounted with said plug in the bore of the body member and rotatable therein. The mixing control member further includes a mixing chamber, two separate inlet passages discharging into the mixing chamber, and an outlet passage discharging from the mixing chamber. Each inlet passage is movable with rotation of the plug in the bore from a closed position to an open position with respect to one of the openings in the wall of the bore. A valve seat is formed at the discharge of the inlet passages, and a valve engageable with the seat is provided.