A technique has been developed to monitor the thrombin generating capacity of plasma (5). A thrombin generation curve (TGC) can be constructed from a sample of plasma and the area under the TGC, called the endogenous thrombin potential (ETP), is a good indicator of the coagulability of the sample. Currently, we have found no published data addressing the TGC in the neonatal population. Therefore, we propose a prospective study between neonates with congenital heart disease presenting for cardiac surgery and other healthy neonates to compare their respective abilities to generate thrombin by measuring TGCs.