We have studied the variation of specific activity of the most important lysosomal enzyme: Cathepsin D. This study has been developed in pig skin incision wounds for its application to the differential diagnosis between vital and postmortem wounds. At the same time, we have determined histamine and serotonine levels to make a comparative study with Cathepsin results. Our results show the utility of this new marker to determine the vitality of wounds, even when the time elapsed until death has been very short. Nevertheless, there is no correlation between Cathepsin D results and those of histamine or serotonin, a fact that induces us to think that this new marker is not useful to determine wound age.