An integrated electro-hydraulic linear actuator without any work fluid reservoir, comprising: - an electric motor of reversible direction of rotation, - a reversible volumetric pump driven by said motor, - a hydraulic cylinder, - a double effect piston and mobile stem in said cylinder separating a first chamber from a second chamber functionally defined on opposite sides of the piston, - a hydraulic circuit driven by said pump for introducing and drawing out hydraulic work fluid to and from said chambers (7, 8) comprising hydraulically piloted valves, - a compressible air chamber of volumetric compensation of thermal expansions/contractions, - hydraulically piloted fluid path selecting means connecting a work fluid side of said compressible air chamber of volumetric compensation to the reversible pump suction branch of the hydraulic circuit, - a pair of hydraulically piloted blocking valves of respective conduits connecting said chambers (7, 8) to inlet/outlet ports of said pump, spring biased safety pressure relief valves in respective by-pass paths between pump suction and pump delivery branches of the hydraulic circuit, wherein a) said stem projects out of only one end of said cylinder and said fluid chambers (7, 8) have identical cross sectional areas; b) said cylinder is solidly connected to a fluid distribution base block associated to a motor-pump assembly split block (4ex1, 4ex2), said mobile stem is tubular, closed at the outer end by a cap and adapter assembly, and sealingly slides in and out of said fixed cylinder and over a fixed inner stem axially extending from said fluid distribution base block and having a longitudinal bore for hydraulically connecting an upper chamber inside the end-capped tubular mobile stem to the hydraulic circuit of the double effect piston, the circular cross sectional area of which is identical to the circular crown area of a lower chamber defined between said tubular mobile stem and said cylinder; characterized in that c) said reversible pump is embedded between a first part (4ex1) and a second part (4ex2) of said split block (4ex1, 4ex2), a shaft of which is driven by said motor through a magnetic coupling installed inside the first part (4ex1) of the motor-pump assembly block; d) at least a compressible air chamber of volumetric compensation of thermal expansions/contractions is defined within one or more internal bores of said first part (4ex1) of said motor-pump assembly block; e) said hydraulically piloted fluid path selecting means are in form of two hydraulically piloted valves adapted to intercept work fluid pathways between the pump delivery branch and the pump suction branch of the hydraulic circuit, respectively, and at least the hydraulic fluid side of a compressible air chamber of volumetric compensation. - an electric motor of reversible direction of rotation, - a reversible volumetric pump driven by said motor, - a hydraulic cylinder, - a double effect piston and mobile stem in said cylinder separating a first chamber from a second chamber functionally defined on opposite sides of the piston, - a hydraulic circuit driven by said pump for introducing and drawing out hydraulic work fluid to and from said chambers (7, 8) comprising hydraulically piloted valves, - a compressible air chamber of volumetric compensation of thermal expansions/contractions, - hydraulically piloted fluid path selecting means connecting a work fluid side of said compressible air chamber of volumetric compensation to the reversible pump suction branch of the hydraulic circuit, - a pair of hydraulically piloted blocking valves of respective conduits connecting said chambers (7, 8) to inlet/outlet ports of said pump, a) said stem projects out of only one end of said cylinder and said fluid chambers (7, 8) have identical cross sectional areas; b) said cylinder is solidly connected to a fluid distribution base block associated to a motor-pump assembly split block (4ex1, 4ex2), said mobile stem is tubular, closed at the outer end by a cap and adapter assembly, and sealingly slides in and out of said fixed cylinder and over a fixed inner stem axially extending from said fluid distribution base block and having a longitudinal bore for hydraulically connecting an upper chamber inside the end-capped tubular mobile stem to the hydraulic circuit of the double effect piston, the circular cross sectional area of which is identical to the circular crown area of a lower chamber defined between said tubular mobile stem and said cylinder; characterized in that c) said reversible pump is embedded between a first part (4ex1) and a second part (4ex2) of said split block (4ex1, 4ex2), a shaft of which is driven by said motor through a magnetic coupling installed inside the first part (4ex1) of the motor-pump assembly block; d) at least a compressible air chamber of volumetric compensation of thermal expansions/contractions is defined within one or more internal bores of said first part (4ex1) of said motor-pump assembly block; e) said hydraulically piloted fluid path selecting means are in form of two hydraulically piloted valves adapted to intercept work fluid pathways between the pump delivery branch and the pump suction branch of the hydraulic circuit, respectively, and at least the hydraulic fluid side of a compressible air chamber of volumetric compensation.