Thrombocytopenia frequently occurs immediately after orthotopic liver transplantation. We have investigated the cause of this phenomenon in a cohort of 45 consecutive liver transplant recipients. The median preoperative platelet count (range) of 129 x 10(9)/l (14-719) fell to 56 x 10(9)/l (23-334) by the fourth postoperative day. The median preoperative reticulated platelet percentage (range) of 6.7% (2.2-23.9) increased to 16.4% (4.6-40.8) on day 7. There was a significant rise in prothrombin fragment F1.2 by the first postoperative day which was followed by rises in fibrinogen and fibrin degradation products. There was no increase in platelet-associated immunoglobulin or markers of endothelial activation. We conclude that there is an increased rate of platelet consumption associated with thrombin generation that reflects the magnitude of liver transplant surgery.