Abstract: A dual-circuit master valve for hydraulically actuated power brakes is diosed. An equalizing device in the valve assures a uniform build-up of pressure in both brake circuits. Even if one brake circuit fails, the equalizing device assures dependable operation of the remaining brake circuit without additional parts. The equalizing device includes at least one pressing member which acts on two conical valve slides, each having an opening facing the pressing member. The end of the pressing member facing the valve slides is provided with elastic material, preferably rubber or plastic, which deforms to equalize pressure when the pressing member presses against the openings in the valve slides.