A hydraulic damper (1, 1a), in particular a motor vehicle suspension damper, comprising a main tube extending along an axis and filed with working fluid, a main piston assembly disposed slidably inside the main tube, attached to a piston rod led outside the hydraulic damper through a sealed piston rod guide, dividing the main tube into a rebound chamber and a compression chamber, and provided with rebound and compression valve assemblies (41, 42) to control the flow of working fluid passing between the rebound chamber and the compression chamber, characterized in that said piston rod is provided with an annular chamber (55, 56, 57) in which a slidable partition is disposed dividing this chamber into a magnetorheological chamber (55, 56), proximal to the main piston assembly and filled with magnetorheological fluid, and a compensation chamber, distal to the main piston assembly and filed with gas, wherein said hydraulic damper (1, 1a) further comprises a secondary piston assembly slidably disposed inside said magnetorheological chamber (55, 56), attached to a secondary piston rod sealingly and slidably guided through the main piston assembly and axially fixed with respect to the main tube, dividing said magnetorheological chamber (55, 56) into a magnetorheological compression chamber, distal to the main piston assembly, and a magnetorheological rebound chamber, proximal to the main piston assembly, wherein said secondary piston assembly is provided with a flow channel and at least one electromagnet coil for variably generating a magnetic flux modifying shear resistance of magnetorheological fluid to control the flow of magnetorheological fluid passing through said flow channel between said magnetorheological rebound chamber and said magnetorheological compression chamber, wherein said at least one electromagnet coil is connected with a control cable passing through said secondary piston rod and led outside the hydraulic damper, wherein said piston rod comprises an extender fixed to the main piston assembly, a cylindrical body fixed to said extender and defining said magnetorheological chamber (55, 56) and said compensation chamber, and a mounting projection fixed to said cylindrical body at its end distal to the main piston assembly. a secondary piston assembly slidably disposed inside said magnetorheological chamber (55, 56), attached to a secondary piston rod sealingly and slidably guided through the main piston assembly and axially fixed with respect to the main tube, dividing said magnetorheological chamber (55, 56) into a magnetorheological compression chamber, distal to the main piston assembly, and a magnetorheological rebound chamber, proximal to the main piston assembly, wherein said secondary piston assembly is provided with a flow channel and at least one electromagnet coil for variably generating a magnetic flux modifying shear resistance of magnetorheological fluid to control the flow of magnetorheological fluid passing through said flow channel between said magnetorheological rebound chamber and said magnetorheological compression chamber, wherein said at least one electromagnet coil is connected with a control cable passing through said secondary piston rod and led outside the hydraulic damper, wherein said piston rod comprises an extender fixed to the main piston assembly, a cylindrical body fixed to said extender and defining said magnetorheological chamber (55, 56) and said compensation chamber, and a mounting projection fixed to said cylindrical body at its end distal to the main piston assembly.