A telescopic hydraulic cylinder includes an inner cylindrical tube and an outer cylindrical tube located concentrically about the inner cylindrical tube, and a guide ring for guiding the inner and outer cylindrical tubes. The guide ring has a cylindrical support surface with a center line and a guide surface and is mounted in a cylindrical groove. The guide surface slides along the inner surface of the outer cylindrical tube or the outer surface of the inner cylindrical tube. The guide surface has a curved surface with a curve radius and a tangent and the tangent to the curved surface and the center line form an inclination angle between zero and five degrees, and the curve radius is larger than the radius of the guide ring in the plane perpendicular to the center line.