The subject of the present invention is, in the most general aspect, the therapeutic application of the Kazal-type serine protease inhibitor Infestin or domains thereof or modified Kazal-type serine protease inhibitors based on Infestin homologs, which prevent the formation and/or stabilization of three-dimensional arterial or venous thrombi by interfering with proteins involved in activation of the so-called intrinsic coagulation pathway. In particular the present invention relates to the use of said Kazal-type serine protease inhibitors or fragments thereof or modified Kazal-type serine protease inhibitors, in the treatment or prophylaxis of a condition or disorder related to arterial thrombus formation, i. e. stroke or myocardial infarction, inflammation, complement activation, fibrinolysis, angiogenesis and/or diseases linked to pathological kinin formation such as hypotonic shock, edema including hereditary angioedema, bacterial infections, arthritis, pancreatitis, or articular gout, Disseminated Intravasal Coagulation (DIC) and sepsis.