Thermostatic mixing valve for sanitary fittings, with a top piece, in which a cone is disposed to be axially movable via a rotatably mounted spindle, and a passage sleeve with windows for the supply of hot and cold water, in which a carriage preloaded via a spring and joined to a thermoelement provided with a control piston is axially movable, wherein the supply of hot and cold water through the windows can be regulated in dependence on the movement of the carriage, wherein the cone (5) comprises a bushing (51), which at its underside turned away from the spindle (2) is closed via a bottom and in which a conical piston (53) is disposed to be axially movable and is preloaded via a spring (54) in the direction of the bottom, wherein a coupling duct is disposed in the bottom in axially aligned manner with the conical piston (53) and which at the same time is axially aligned with the control piston (81) of the thermoelement, and into which the conical piston (53) and/or the control piston (81) of the thermoelement (8) can be moved, and wherein, in an upper position of the carriage (7) (hot-water position), the control piston (81) bears on the conical piston (53) and the bottom is spaced apart from the carriage (7) and, in a lower position of the carriage (7) (cold-water position), the control piston (81) is spaced apart from the conical piston (53) and the bottom rests on the carriage (7).