A coupling for use with pressurized systems permitting coupling of valved coupling parts even though one of the parts may be under high pressure. An axially reciprocal valve (28') which automatically opens upon the coupling halves being connected is guided within a shell (50) within the pressurized coupling half and a sealed relationship between the valve and shell minimizes the area of valve surfaces exposed to the pressurized medium reducing the axial forces imposed upon the valve toward the closed position. A bleed valve (64) communicating with the valve interior permits valve operation with hydraulic systems in the event of seal leakage.