Five monkey recipients of a porcine renal xenograft were studied to determine the relationship between fibrin formation in acute humoral xenograft rejection (AHXR) and procoagulant and anticoagulant factor levels to establish whether changes in coagulation parameters could be used to predict AHXR and determine whether AHXR is associated with overt disseminated intravascular coagulopathy (DIC) in this model. Variable degrees of compensated consumptive coagulopathy were observed in each primate. Elevated thrombin-antithrombin (TAT), F1+2 and D-dimer levels consistent with thrombin generation and fibrin formation were recorded. There was no consumption of the main clotting inhibitors (including antithrombin) or a progressive, severe drop in fibrinogen levels and platelet counts, although grafts were left in situ. After transplantation, D-dimer levels remained persistently high, so they were of limited value in defining this coagulopathy. At post mortem, no cases of multiorgan involvement typical of overt DIC were observed. The lack of a rapid postoperative recovery of clotting inhibitor levels after transplantation was invariably associated with early poor outcome. This study shows that AHXR is associated with various degrees of compensated consumptive coagulopathy in our pig-to-primate model. No clear relationship was found between coagulation parameter levels and graft outcome.