A mixing valve has a housing having hot- and cold-water inlets and at least one hot-, cold-, or mixed-water outlet. Respective hot- and cold-water valves in the housing each have a valve stem rotatable to control flow through the respective valve and carrying a respective externally toothed gear. Respective hot- and cold-water control rings rotatably mounted about a common axis on the housing each have internal teeth in continuous mesh in all angular positions of the valves and rings with the gears of the respective valves.