A wrist prosthesis having a distal supporting part and a part for proximal support of the prosthesis on both the radius and the ulna. The proximal part of the prosthesis may be a plate configured to be supported on substantially unaltered surfaces of the radial and ulnar epiphyses when the radius and ulna are fused at the radial-ulnar joint. The distal part of the prosthesis may be shaped to be supported by surfaces on at least three of the distal carpal bones. The prosthesis may include an intermediate component having a receptacle portion distally defining a concave bearing surface. The distal part may have a proximal side defining an ellipsoidal convex bearing surface having a generally part-circular cross-section. This invention also provides a method of implanting a wrist prosthesis which is configured to be attached to the distal ends of the radius and ulna which includes the steps of fixably attaching the prosthesis to the ends of the radius and ulna and removing a segment of the ulnar diaphysis to permit supination and pronation.