Thrombophilic risk factors of the vascular system are not as well defined as the classic risk factors of atherosclerosis or the thrombophilic risk factors of the venous system. Until now, the assessment is complicated by an inadequate differentiation between (a) proatherosclerotic and prothrombogenic effects (i. e. platelet receptor polymorphisms) and (b) reactive alterations of a haemostatic parameter (i. e. PAI-1, Fibrinogen) as an expression of an acute phase reaction and primary hereditary changes of those risk determinants. Actual data indicate for the majority of the potential risk factors only a mildly increased relative risk for an arterial ischaemic event and are often inconsistent. Anyhow, the impact of potential thrombophilic risk factors for the arterial vascular occlusion is not excluded. A possible reason is, that conventional case-control studies cannot identify risk factors of thrombogenicity in the arterial system unless they ore also risk factors of atherosclerosis.