The relation between the ABO blood group and hemostasis has been predominately attributed to the fact that in non-O individuals the plasma levels of FVIII-von Willebrand Factor (VWF) complexes are approximately 25% higher than in O individuals [9, 11], as it is known that elevated VWF and FVIII levels are associated with venous thromboembolism and coronary heart disease whereas low levels cause a bleeding tendency [4, 12–16]. Here, VWF is linked to venous thromboembolism.