The distribution of the proteinase inhibitors alpha-1-antichymotrypsin (alpha 1-act), alpha-2-macroglobulin (alpha-2-m) and lysozyme was analysed immunohistochemically in 27 intravitally acquired wounds, 3 postmortem skin lacerations and 9 specimens of undamaged skin. Intravitally acquired wounds demonstrated distinct positive reactions for all antibodies examined (alpha-1-act 66.6%; alpha-2-m 51.9%; lysozyme 25.9%). However the undamaged skin margins opposite the wound margins also gave positive reactions (alpha-1-act 51.8%; alpha-2-m 37.0%; lysozyme 25.9%). Nearly half of the control cases (specimens of undamaged skin) exhibited weak positive reactions for all 3 antibodies. These could be easily distinguished from the strong positive reactions observed in intravitally acquired wounds. False positive reactions were observed due to contamination resulting from contact with serum components, in cases of advanced autolysis of specimens, and as a result of fixation and drying artefacts. Even though immunohistochemical studies of alpha-1-act, alpha-2-m and lysozyme give some indications concerning wound vitality, they cannot be considered as proof because irrefutable differentiation of true positive and false positive reactions is not possible in all cases.