Abstract: A barrier and lubrication fluids pressure regulation system for a subsea motor and pump module is disclosed, comprising a lubrication fluid circuit in flow communication with a hydraulic fluid supply via a first pressure reducing regulator (15); and a barrier fluid circuit in flow communication with the hydraulic fluid supply via a second pressure reducing regulator (14). The first pressure reducing regulator (15) is configured to reduce the supply fluid pressure in response to the pumped medium pressure at the suction side (4) or at the discharge side (5) of the pump, and the second pressure reducing regulator (14) is configured to reduce the supply fluid pressure in response to the output pressure of the first pressure reducing regulator (15). A pressure regulation unit is likewise disclosed, and arranged for housing the components of the barrier and lubrication fluids pressure regulation system in a pressurized vessel.