The present invention refers to a thoracic prosthesis constituted by a right hemisphere ED and a left hemisphere ES joined together, or to only one of the two hemispheres, or to only one portion of the latter. The present invention further relates to a method for the preparation of a synthetic thoracic prosthesis PT constituted by a right hemisphere ED and a left hemisphere ES joined together by only one of the two hemispheres or by a single portion of the latter; all of the above being prepared without any direct interaction with human body and prior to implantation therein.