The invention relates to a hydro-pneumatic piston accumulator (1), particularly for vehicle suspension systems, consisting of an accumulator housing (2) and a separating piston (6), which is disposed free-floating inside the accumulator housing in a displaceable manner in the direction of the movement axis (4). The separating piston separates an accumulator area (8) for a hydraulic medium from a pressure area (10) that is filled or is to be filled with a compressible medium, and is guided with an interior guide opening (30) on an elongated guide element (32), which is axially fixed within the accumulator housing (2).