Impaired haemostasis has been reported in children with congenital heart disease undergoing cardiopulmonary bypass. As thrombin generation encompasses all phases of the coagulation process, this analysis might provide the best assessment of global haemostasis. A prospective study was undertaken to test the hypothesis that thrombin generation reveals an impaired haemostasis after paediatric cardiac surgery and that ex-vivo addition of platelet concentrate and haemostatic agents improves thrombin generation. The study comprised 29 children with congenital heart disease, who underwent corrective surgery including cardiopulmonary bypass. Thrombin generation was analysed both in platelet-poor plasma and platelet-rich plasma. Analysis of the thrombin generation showed a significantly prolonged lag time (P_{platelet-poorandplatelet-richplasma} < 0.001), decreased peak thrombin generation (P_{platelet-poorplasma} = 0.013; P_{platelet-richplasma} < 0.001) as well as a decreased endogenous thrombin generation potential (P_{platelet-poorandplatelet-richplasma} < 0.001) after cardiopulmonary bypass compared to baseline. Ex-vivo addition of platelet concentrate, fibrinogen concentrate and recombinant factor VIIa improved thrombin generation significantly (all P < 0.001). Changes were most pronounced after addition of platelet concentrate. The present study showed that thrombin generation was significantly reduced after cardiopulmonary bypass in children, both when analysed in platelet-poor and platelet-rich plasma. The impaired haemostasis was not only restored after ex-vivo addition of platelet concentrate but also rVIIa improved the haemostatic capacity.