 Coagulation abnormalities after pediatric open-heart surgery are complex and very often multifactorial. Besides the cardiopulmonary bypass CPB, the congenital pathology and the coagulation tests during CPB, the younger age has been the most significant risk factor for bleeding and transfusion requirements. In children the volume of pump priming is much higher compared with the patients circulating blood volume. For this reason the CPB tubing system is primed with packed red blood cells and fresh frozen plasma FFP to avoid excessive hemodilution and induced coagulopathy. While this is routinely performed in neonates and small infants, the routine priming of CPB system with FFP has been questioned in several randomized prospective studies in older infants. However, the results of these studies are conflicting. Moreover, they show methodological issues. 