Abstract: A hydraulic trench support includes a piston and cylinder head supported within a cylinder such that the cylinder head is fixed at one end of the cylinder and the piston is moveable within the cylinder. A piston rod is coupled to the hydraulic piston at one end and extends outside the cylinder and beyond at the other end. A pair of load bearing bases having generally planar construction are attached to the piston rod portion extending beyond the cylinder and to the cylinder head. Means are provided for introducing a fluid under pressure into the cylinder between the inwardly facing surfaces of the cylinder head and piston to provide an outwardly expanding force there between which is coupled to the base members to provide a sidewall retaining force. In one embodiment, spring means are provided which bias the hydraulic trench support toward a contracted position in the absence of fluid pressure.