A total of 39 vital human skin wounds (20 cases with short survival times ranging from a few seconds to approximately 30 min and 19 cases with wound ages between 50 min and 13 days) were investigated. Alpha 1-antichymotrypsin (A1-ACT) was visualized by immunohistochemistry. Additionally, fibronectin was localized in 13 of these wounds (8 cases with short and 5 cases with longer survival times). Furthermore, 13 postmortem lesions (stab wounds) were removed from corpses approximately 4 h after infliction and analyzed for A1-ACT and fibronectin. The "vital" reaction previously described for A1-ACT in form of a band-shaped staining pattern at the wound edges was observed in both vital wounds and in most postmortem lesions. A similar reaction was also obtained for fibronectin in wounds inflicted after death, but could be unambiguously distinguished from vital fibronectin staining by morphological criteria. Therefore, it seems questionable that the vitality of skin wounds can be determined by the immunohistochemical detection of A1-ACT and probably other proteinase inhibitors. The meaning of the localization of fibronectin for the determination of the vitality of human skin wounds with a survival time of at least a few minutes could be confirmed.