Abstract: An endoprosthetic elbow joint in the form of a one-piece endoprosthesis having at least one hinge joint provided with anchoring shanks of which one is to be connected to the humerus and of which the other is to be connected to the ulna of a patient, the axis of the hinge joint taking the place of the flexing and extending axis of the natural arm. According to the invention, the end of the hinge joint on the side on which the patient's radius will be situated continues into a rotary humeroradial joint which is rigidly connected to the hinge joint. The rotary joint has at least two degrees of freedom, one of which allows pivoting movement of the joint by a shank thereof for anchoring in the radius about the flexing and extending axis of the hinge joint and of which the other allows rotary movement by the shank about the longitudinal axis of the patient's radius.