Abstract: Known two-circuit pressure regulators with differential pressure warning indicators are very expensive with regard to production and unreliable with regard to operation. To eliminate these disadvantages, the two-circuit pressure regulator with a differential pressure warning indicator disclosed herein includes an annular leak indication piston having a bore therein that supports and guides the piston shafts of the two regulator valves. The annular piston is so designed that with approximately equal pressures in both brake circuits the annular piston independently assumes its usual central rest position.