Abstract: A rotary damper comprises a stator and a rotor which are co-axial, circular and cylindrical, two extreme faces substantialy transversal to the axis of the stator and rotor and disposed respectively on either side of the stator and rotor, a main chamber filled with a fluid, defined between the extreme faces and the stator and the rotor, blades disposed on the stator and rotor and dividing the main chamber is a plurality of volumes, the blades laminating the flow of fluid through the different volumes of the main chamber, and an auxiliary chamber which communicates with the main chamber. The auxiliary chamber is at least partly formed by a diaphragm which is elastically deformable and which is designed to compensate for the volume variations of the fluid as a function of its temperature, and to bring in, if necessary, a twisting stiffness in parallel to the damping function. The rotary damper finds application for example in vehicle suspensions.