Abstract: Total heart prosthesis including a casing implantable in the pericardial cavity, the geometry of which is similar to that of the natural heart, with a motor device inside the casing which essentially includes two membranes, one of which works during the elongation stroke within a space defining the right ventricle and the other of which works during the deformation stroke within a space defining the left ventricle. Blood bags are enclosed within the right and left ventricular spaces adapted to be connected to vessels of the circulatory system of a patient. The membrane of the right ventricle and a support associated therewith are mounted within the prosthesis casing such that the movement of the membrane during the elongation stroke (systole) is broken down into two phases, one of which is a displacement without elongation and the other, only, is accompanied with an elongation.