A piston-cylinder unit includes: a cylindrical pressure tube having a first end side defining an end side opening; a piston, axially displaceable in the pressure tube, the piston having a piston rod, the piston rod being guided out of the pressure tube at the first end side through the end side opening; a piston rod guide and a piston rod seal, arranged inside the pressure tube, which cooperate together to sealingly guide the piston rod at the end side opening; and a cup-like protective cap surrounding an end region of the cylindrical pressure tube from the first end side, the protective cap having a base at its end, the base having a coaxial through-orifice having an inner wall through which the piston rod extends in a displaceable manner. The inner wall of the through-orifice tightly surrounds the piston rod.