Non-glutaraldehyde fixation of an organ or a prosthesis for implantation in a mammal is based upon carbodiimide treatment. A solution containing a sterilizing agent, such as EDC, in combination with a coupling enhancer, such as Sulfo-NHS, and a high concentration of a diamine cross linking agent is used. As a result, only minimal surface reduction occurs during fixation, and the resultant products show a dramatic increase in resistance to calcification.